An analysis of 360 GPU (Xenos)

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

HarakoMeshi

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

HarakoMeshi

thats total BS. many posters before you, and including the author and posters on B3d have shot this down. posting a comment with no answer yet does not let you free to post this as fact. you could be very well wrong and most likely are. second in the article itself the author explains why the GPU in the 360 can actually output 1080p better than the PS3. and third every single multiplatform game on the 360 and PS3 looks much worse on the PS3. fourth the PS# will never have as high resolution textures automaticaly making the discussion void. a game is composed of 100% textures. if those are uglier than its no competition.

 actually what we can do, is wait until someone comments to his post on that site. then the argument can come back up again. you cannot make a post, take it and run. i completly respect your post, i just want someone elses "attack" first. and by the way the RSX cannot adress all the 512 ram. that has been mostly discussed.

i really wish i knew what you're talking about, all those numbers and theoretical possibillities confuse me. guess i'll just look at Call of Duty 3 for a real world comparison.

here's looking at the 360 version. nice

here's looking at the PS3 ver....hey wait a minute, what's goin on here. well, this doesn't make any sense now does it, what were all those numbers he was talking about.....

how can the RSX access 512 mb of memory when it only have 256mb of memory. the 360 has 512 of shared memory so only its GPU should possibly access 512mb Nugtoka

[QUOTE="Nugtoka"]how can the RSX access 512 mb of memory when it only have 256mb of memory. the 360 has 512 of shared memory so only its GPU should possibly access 512mb HarakoMeshi

but that is your main point and its wrong. i do not know how to go into details frankly. i dont. im being honest, but that argument has happened on B3D soooooo many times and was proven that this is the main reason why the 360 outputs higher resolution textures. but seriously dude wait til someone answers your post on the site. they will.

[QUOTE="HarakoMeshi"]

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

A-LEGEND

thats total BS. many posters before you, and including the author and posters on B3d have shot this down. posting a comment with no answer yet does not let you free to post this as fact. you could be very well wrong and most likely are. second in the article itself the author explains why the GPU in the 360 can actually output 1080p better than the PS3. and third every single multiplatform game on the 360 and PS3 looks much worse on the PS3. fourth the PS# will never have as high resolution textures automaticaly making the discussion void. a game is composed of 100% textures. if those are uglier than its no competition.

sony hasnt released teh specs themselves because they are afraid of the comparison.A-LEGEND

[QUOTE="A-LEGEND"][QUOTE="HarakoMeshi"]

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

HarakoMeshi

thats total BS. many posters before you, and including the author and posters on B3d have shot this down. posting a comment with no answer yet does not let you free to post this as fact. you could be very well wrong and most likely are. second in the article itself the author explains why the GPU in the 360 can actually output 1080p better than the PS3. and third every single multiplatform game on the 360 and PS3 looks much worse on the PS3. fourth the PS# will never have as high resolution textures automaticaly making the discussion void. a game is composed of 100% textures. if those are uglier than its no competition.

that is literaly impossible. you cannnot just divide a GPUs performance by 3. thats why i said lets wait until someone answers on the site you posted it on. you said yourself your assuming. so before making this post, and taking it to teh people lets have it verified.

[QUOTE="A-LEGEND"]sony hasnt released teh specs themselves because they are afraid of the comparison.crazyberrywater

The article on B3D is always evolving and the author did not have all of the facts from the beginning for example he was not aware that the PS3 GPU could use all 512MB of PS3's memory but was later corrected and he ammended the article. In the same way he needs to account for the Xenos tiled rendering, which incidentally I believe was discussed by Mike Abrash in the past. HarakoMeshi

we shall see. i said. wait until someone answers. you admited yourself your assuming.

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

HarakoMeshi

[QUOTE="HarakoMeshi"][QUOTE="A-LEGEND"][QUOTE="HarakoMeshi"]

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

A-LEGEND

thats total BS. many posters before you, and including the author and posters on B3d have shot this down. posting a comment with no answer yet does not let you free to post this as fact. you could be very well wrong and most likely are. second in the article itself the author explains why the GPU in the 360 can actually output 1080p better than the PS3. and third every single multiplatform game on the 360 and PS3 looks much worse on the PS3. fourth the PS# will never have as high resolution textures automaticaly making the discussion void. a game is composed of 100% textures. if those are uglier than its no competition.

that is literaly impossible. you cannnot just divide a GPUs performance by 3. thats why i said lets wait until someone answers on the site you posted it on. you said yourself your assuming. so before making this post, and taking it to teh people lets have it verified.

[QUOTE="HarakoMeshi"]

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

FrYGuY101

Games look good, so I am happy about teh 360's powa.

[QUOTE="A-LEGEND"][QUOTE="HarakoMeshi"][QUOTE="A-LEGEND"][QUOTE="HarakoMeshi"]

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

HarakoMeshi

thats total BS. many posters before you, and including the author and posters on B3d have shot this down. posting a comment with no answer yet does not let you free to post this as fact. you could be very well wrong and most likely are. second in the article itself the author explains why the GPU in the 360 can actually output 1080p better than the PS3. and third every single multiplatform game on the 360 and PS3 looks much worse on the PS3. fourth the PS# will never have as high resolution textures automaticaly making the discussion void. a game is composed of 100% textures. if those are uglier than its no competition.

that is literaly impossible. you cannnot just divide a GPUs performance by 3. thats why i said lets wait until someone answers on the site you posted it on. you said yourself your assuming. so before making this post, and taking it to teh people lets have it verified.

we will see. if you are right. the only devs who have had their game lower resolution than 720p happen, are EA and admitted it was an error on their part. so again im waiting for an answer on someone elses part.

[QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"]

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

HarakoMeshi

whats funny is that on B3d NOBODY has ever suggestedt he 10mb EDRAM was too little. they have always been praising it.

[QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"]

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

HarakoMeshi

This is pointless, it took far more clever people than I, you or anyone from these various sites to create the xenos.

Please pay attention, Ati have been (in some areas) ahead of Nvidia in the pc market for years FACT.

The best example of this is the ability to do HDR + AA at the same time.

None of use truely can or will ever understand the arcitecture used and why?

All i know is it Rocks!

[QUOTE="HarakoMeshi"][QUOTE="A-LEGEND"][QUOTE="HarakoMeshi"][QUOTE="A-LEGEND"][QUOTE="HarakoMeshi"]

This is my rant about the Xbox 360 GPU http://dpad.gotfrag.com/portal/story/35372/?cpage=2#comment_6047197 (in the comments section).  If someone knows some technical details that I don't about the 360 please let me know.  Based on the public information about the 360 Xenos GPU I have made my deductions.  I am an experienced developer in 3D graphics on consoles and I have tried to make my calculations accurate but I may have made a mistake if there is some mystery of 360 I do not understand.

---

The Xenos GPU has an unprecendented bandwidth to it's 10MB of EDRAM of 256MB/s. If I understand correctly this peak bandwidth is actually only available when dong 4xMSAA. The actual writing bandwidth from the GPU is 32GB/s. This number is then multiplied by 8 to account for 4XMSAA times 2 for read+write operations.

Now if we consider the size of a full picture at 720p resolution (1280x720) with 8 bytes per pixel (color + Z) it almost fills the 10MB edram (over 7MB). In order to render that same picture with 4xMSAA four times the memory is required (over 28MB). This is the dilemma for the Xenos. In order to render such HD picture with AA it must do it in sections - in this case 3 sections.

This slicing is where Xenos pays the price. The developer must jump through hoops to render their scenes multiple times (actually I believe the Xbox 360 APIs take care of some of the work), but all this rendering multiple times is not free. All the geometry processing is duplicated, all the GPU state changes & texture changes are duplicated and so on. The only parts that are not duplicated are the pixels. So this will eat into the Xenos' edge over the RSX. In fact if whole scenes must be rendered 3 times we find that the effectove Xenos triangle setup rate now becomes lower than the RSX.

So the answer is that most developers probably won't render full 720p with 4XAA on the 360. They may drop below 720p or they may drop the AA. 720p with 2XAA still requires 2 passes. A possible resolution achievable in one pass could be 1024x576 with 2xAA. Anything higher would require multiple passes.

Instantly we see that anything using 4XAA is overbooking the size of the EDRAM, while using anything less than 4XAA is underusing the EDRAM bandwidth. In fact the Xenos is not even equipped to render 480p with 4XAA in a single pass (requires 10.5MB). A slight design flaw there.

The RSX can address the full 512MB of the PS3 so it has no such issues with frame buffer size.

So you see there is a tradeoff with the 360 GPU. You can render true 720p at a rate perhaps comparable to the RSX or slower. Or you can render 720p without any AA, or 60% below 720p with only 2xAA - really fast. This is the contradiction of the Xenos' design: so much power but a limited space to use it in. For the Xenos design to have been perfectly suited to the 360, over 28MB of EDRAM would have been required.

Taking things in context, these days consumers complain if there is no AA. And also in context I think consumers would be a bit annoyed to find out that 360 games are not truly 720p. So, developers have little choice but to please consumers with HD and AA and sacrifice their Xenos performance to do slicing & dicing. With this in mind, do not expect the 360 to beat the PS3 in graphics terms unless the 360 game is actually well below 720p.

Just some food for thought, in order to render 1080p with 4X AA would require 7 passes on the Xenos, so even if the Xenos setup rate was 4 times faster than the RSX it would still be the underdog. While on the cover it seemed the Xenos would have been better at doing 1080p than the RSX, things are not what they appear when considering all factors.

A-LEGEND

thats total BS. many posters before you, and including the author and posters on B3d have shot this down. posting a comment with no answer yet does not let you free to post this as fact. you could be very well wrong and most likely are. second in the article itself the author explains why the GPU in the 360 can actually output 1080p better than the PS3. and third every single multiplatform game on the 360 and PS3 looks much worse on the PS3. fourth the PS# will never have as high resolution textures automaticaly making the discussion void. a game is composed of 100% textures. if those are uglier than its no competition.

that is literaly impossible. you cannnot just divide a GPUs performance by 3. thats why i said lets wait until someone answers on the site you posted it on. you said yourself your assuming. so before making this post, and taking it to teh people lets have it verified.

we will see. if you are right. the only devs who have had their game lower resolution than 720p happen, are EA and admitted it was an error on their part. so again im waiting for an answer on someone elses part.

some of you guys are acting like the ps3 has 512 megs of ram that is ready to be used, this is not the case at all. you have to take into account the background memory usage from both OS's. i think the numbers were 96 megs and 16 megs for both OS's to be running in the background at all times. so what it comes down to is the ps3 has its 256 meg videocard, and about 144 megs of system ram to play with.jxditu

you couldnt be more wrong tc. If you tile correctly the problems go away, there is no performance loss noremorse18

[QUOTE="noremorse18"]you couldnt be more wrong tc. If you tile correctly the problems go away, there is no performance loss HarakoMeshi

[QUOTE="HarakoMeshi"][QUOTE="noremorse18"]you couldnt be more wrong tc. If you tile correctly the problems go away, there is no performance loss FrYGuY101

[QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"][QUOTE="noremorse18"]you couldnt be more wrong tc. If you tile correctly the problems go away, there is no performance loss HarakoMeshi

Ok the following is an example I found of a developer actually struggling with the 360 because of this tiling problem.

http://digg.com/gaming_news/Xbox_360_Too_Weak_To_Handle_720p_Games

You can see that they were forced to reduce the resolution of their games CoD3 and Tony Hawks 8.  So I am not crazy after all....

[QUOTE="HarakoMeshi"][QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"][QUOTE="noremorse18"]you couldnt be more wrong tc. If you tile correctly the problems go away, there is no performance loss FrYGuY101

[QUOTE="jxditu"]some of you guys are acting like the ps3 has 512 megs of ram that is ready to be used, this is not the case at all. you have to take into account the background memory usage from both OS's. i think the numbers were 96 megs and 16 megs for both OS's to be running in the background at all times. so what it comes down to is the ps3 has its 256 meg videocard, and about 144 megs of system ram to play with.HarakoMeshi

Ok the following is an example I found of a developer actually struggling with the 360 because of this tiling problem.

http://digg.com/gaming_news/Xbox_360_Too_Weak_To_Handle_720p_Games

You can see that they were forced to reduce the resolution of their games CoD3 and Tony Hawks 8.  So I am not crazy after all....

HarakoMeshi

[QUOTE="HarakoMeshi"]

Ok the following is an example I found of a developer actually struggling with the 360 because of this tiling problem.

http://digg.com/gaming_news/Xbox_360_Too_Weak_To_Handle_720p_Games

You can see that they were forced to reduce the resolution of their games CoD3 and Tony Hawks 8.  So I am not crazy after all....

FrYGuY101

[QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"]

Ok the following is an example I found of a developer actually struggling with the 360 because of this tiling problem.

http://digg.com/gaming_news/Xbox_360_Too_Weak_To_Handle_720p_Games

You can see that they were forced to reduce the resolution of their games CoD3 and Tony Hawks 8.  So I am not crazy after all....

HarakoMeshi

[QUOTE="HarakoMeshi"][QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"]

Ok the following is an example I found of a developer actually struggling with the 360 because of this tiling problem.

http://digg.com/gaming_news/Xbox_360_Too_Weak_To_Handle_720p_Games

You can see that they were forced to reduce the resolution of their games CoD3 and Tony Hawks 8.  So I am not crazy after all....

FrYGuY101

[QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"][QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"]

Ok the following is an example I found of a developer actually struggling with the 360 because of this tiling problem.

http://digg.com/gaming_news/Xbox_360_Too_Weak_To_Handle_720p_Games

You can see that they were forced to reduce the resolution of their games CoD3 and Tony Hawks 8.  So I am not crazy after all....

HarakoMeshi

[QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"][QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"]

Ok the following is an example I found of a developer actually struggling with the 360 because of this tiling problem.

http://digg.com/gaming_news/Xbox_360_Too_Weak_To_Handle_720p_Games

You can see that they were forced to reduce the resolution of their games CoD3 and Tony Hawks 8.  So I am not crazy after all....

HarakoMeshi

how can the RSX access 512 mb of memory when it only have 256mb of memory. the 360 has 512 of shared memory so only its GPU should possibly access 512mb Nugtoka

http://www.beyond3d.com/articles/xenos/ This is the best artical, and the major points: -8 ROPs are @ 5% loss 4xAA+HDR @ 720p -48 Shaders each with 4 FP ALUs (each G80 shader has one FP ALU) -eDram from the ROPs to the framebuffer 256gb/s bandwidth -All 512MB of memory is free, OS is running off the 16MB flash chip -96 billion shader ops per seconddracolich666

[QUOTE="Nugtoka"]how can the RSX access 512 mb of memory when it only have 256mb of memory. the 360 has 512 of shared memory so only its GPU should possibly access 512mb navneet21