Yep, I agree that a VLIW4 GPU is a bit more future-proof than a VLIW5.
FWIW, I didn't get the impression that crazycheese was planning to buy an HD58xx, just wondering what performance was like these days.
Announcement
Collapse
No announcement yet.
Anyone with HD5870 or HD5850 using recent opensource driver and kernel?
Collapse
X
-
Originally posted by bridgman View PostQ's point about the Cayman shader core being able to execute 4 complex operations in a single instruction is correct in principle, however I don't believe the current compiler is able to pack multiple operations into a single instruction. Not sure if the llvm compiler paths are able to do that yet either.
When we looked a couple of years ago the average open source compiler utilization was a bit under 3 while the proprietary shader compiler was a bit under 4. With the trend to more complex shaders I imagine both numbers have gone down a bit further since then.
I just don't want him to buy a hd5000 card because its technically bullshit in a modern world of more and more complex shaders.
If he buy a hd7970 he buy 4 shaders and use 3-3.5 then he lost only 1-0,5 instead of you buy 5 shaders and only use 2-3 and lost 2-3
Leave a comment:
-
Originally posted by necro-lover View Postthe catalyst do replace complex shaders with simple shaders for hd2000-hd5000 for every single app.
Originally posted by necro-lover View Postthe average for catalyst is 3,5 catalyst use 3,5 of 5 per group for 5D VLIW and 3,5 of 4 for 4D VLIW
this means 5D VLIW is useless even for the catalyst.
In general VLIW5 was better for pure graphics workloads, but as compute became a larger part of GPU workload (there's a lot of compute hidden in modern graphical apps as well) then VLIW4 became a better fit.Last edited by bridgman; 15 September 2012, 02:36 PM.
Leave a comment:
-
Originally posted by crazycheese View PostHmm, thanks!
Maybe this is the cause for opensource radeon being slow?
Originally posted by crazycheese View PostI remember someone (Marek?) said that "we don't have efficient shader compiler"...
the catalyst do replace complex shaders with simple shaders for hd2000-hd5000 for every single app.
Originally posted by crazycheese View PostSo opensource driver simply uses 1 of 5 units and the simpler are utilized randomly?
Originally posted by crazycheese View PostIf catalyst can break or cheat the complex into simpler, it will approach 3,5-4 (out of 5) load compared to 1-2.5(out of 5) load(performance) on opensource. Wild claim here..
this means 5D VLIW is useless even for the catalyst.
yes in the worst case the opensource driver use 1 of 5 for 5D VLIW and with a shader compiler in the future 3,5 of 4 for the 4D VLIW
now you get what? hd2000-hd5000 will never ever get a improvement because you need a shader replacement to load the 4 simple shader units per group.
this means for the open-source driver its complete stupidity to buy a hd5000 because you will not get any improvement because they will not build a per app shader replacement infrastructure.
you will get a good result with a hd6970 with the future shader compiler.
Originally posted by crazycheese View PostTo support (or deny) this, one should extensively test 4D(0/4) hardware with opensource and catalyst, and compare it to good 5D(4/1) VLIWs.
they switch from 5D to 4D and complex shader only because even the catalyst CAN NOT HANDLE THIS COMPLEXITY of shader replacement and compiling for 2 different kind of shaders.
Originally posted by crazycheese View PostTest of any HD5xxx, HD64xx-68xx VS HD69xx (only three cards available, all high-end). If the performance of opensource and catalyst is much closer to each on HD69xx, then you are correct...
a example of lowend 4D VLIW: AMD A6-3420M AMD Radeon HD 7470M
Leave a comment:
-
Originally posted by curaga View PostIndeed until recently, I believe the open driver only scheduled one of the five units.
A more capable compiler could help with the first case by packing multiple single component operations into a single instruction, but couldn't do much about the second case where the T unit was required. That said the second case didn't happen too much for graphics -- it was mostly compute workloads that justified moving from 4 simple +1 special to 4 identical ALUs.
Q's point about the Cayman shader core being able to execute 4 complex operations in a single instruction is correct in principle, however I don't believe the current compiler is able to pack multiple operations into a single instruction. Not sure if the llvm compiler paths are able to do that yet either.
When we looked a couple of years ago the average open source compiler utilization was a bit under 3 while the proprietary shader compiler was a bit under 4. With the trend to more complex shaders I imagine both numbers have gone down a bit further since then.Last edited by bridgman; 15 September 2012, 02:29 PM.
Leave a comment:
-
Indeed until recently, I believe the open driver only scheduled one of the five units. The LLVM VLIW packetizer should be enabled in current git, so it should now use more units, but it's likely not close to Catalyst-level efficiency.
Leave a comment:
-
Hmm, thanks!
Maybe this is the cause for opensource radeon being slow? I remember someone (Marek?) said that "we don't have efficient shader compiler"...
So opensource driver simply uses 1 of 5 units and the simpler are utilized randomly?
If catalyst can break or cheat the complex into simpler, it will approach 3,5-4 (out of 5) load compared to 1-2.5(out of 5) load(performance) on opensource. Wild claim here..
To support (or deny) this, one should extensively test 4D(0/4) hardware with opensource and catalyst, and compare it to good 5D(4/1) VLIWs.
Test of any HD5xxx, HD64xx-68xx VS HD69xx (only three cards available, all high-end). If the performance of opensource and catalyst is much closer to each on HD69xx, then you are correct...Last edited by crazycheese; 15 September 2012, 12:31 PM.
Leave a comment:
-
Originally posted by crazycheese View PostYes, I know, but I need some real-life FPS. Not much has changed since 5870.
The GCN is in heavy works right now, unusable true,.. still.. based upon approximation from evergreen surfacing to its current support, it will take at least 1.5 years. A GCN card bought right now, in 1.5 years, is already outdated. This is why, for opensource GCN is excluded from the list.
Also, evergreen still has, hardware-sided, good energy consumption (would become even better, if they finally switch to dynprofiles), good 3d performance, and ability to drive multiple displays which works and some opencl work is going on.
Yes, this is exactly like 3 years ago, where AMD consumers were forced to purchase old cards if they want opensource, but at least the hardware stopped sucking now.
A possible candidate is 5870 eyefinity version with 2GiB of vram.
this is wrong 5870 is 1 big(complex) 4 little(simple) VLIW shader units.
a 6970 is 4 big complex shader units. without little simple shader units.
in the reality they just use the 1 big shader unit and ignore the simple little simple shaders
this means the hd6970 is easier to write a compiler for because you don't have to care about this.
also the full utilization per shader cluster is higher in 4D-VLIW than in 5D-VLIW average is ~3,5
this means you lose 5-3,5=1,5 for 5D VLIW and only 0,5 for 4D-VLIW
in other words you are stupid if you think a hd5870 is a option instead if a hd6000 card.
if a complex shader hits your pipe you do only have 1/5 performance with a 5D-VLIW architecture the 4D-VLIW do not have the same problem because there are 4 complex shaders instead.
the catalyst do have some dirty shader compiler tricks with shader replacement to cheat with the replacement of complex shaders with simple shaders. that?s why the catalyst is so much faster.
but even with the catalyst the 4D-VLIW win because of the average utilizatio of 3.5... this means 5D-VLIW worth nothing.
Leave a comment:
-
Yes, I know, but I need some real-life FPS. Not much has changed since 5870.
The GCN is in heavy works right now, unusable true,.. still.. based upon approximation from evergreen surfacing to its current support, it will take at least 1.5 years. A GCN card bought right now, in 1.5 years, is already outdated. This is why, for opensource GCN is excluded from the list.
Also, evergreen still has, hardware-sided, good energy consumption (would become even better, if they finally switch to dynprofiles), good 3d performance, and ability to drive multiple displays which works and some opencl work is going on.
Yes, this is exactly like 3 years ago, where AMD consumers were forced to purchase old cards if they want opensource, but at least the hardware stopped sucking now.
A possible candidate is 5870 eyefinity version with 2GiB of vram.
Leave a comment:
-
Originally posted by crazycheese View PostI was wondering what is current realistic performance on this card using lastest stack?
Lightsmark and Xonotic are of relevance for me.. 1600, 1920 or similar; high or ultra.
I couldn't find any information on openbenchmarking or via google. The only part that comes close is this
Anyone?
its because of the shader compiler and the hd6970 do have the most advanced and most "easy" to program VLIW shader core.
Its still a full joke to the hd7000 series technically but the hd7000 series is not ready to use right now.
In my benchmark research the hd4000 series is one of the worst performers and the hd6970 is the best right now.
people with much lower hardware than your old hd4770 with the 6000series get much better benchmark results. Its just 3-4 times faster on similar hardware specifications. the performance difference is "criminal" they just betrayed there hd4000 customers.
I personally would not waste my money on a death horse like VLIW ... you'll regret it because amd will make sure you'll regret it.
Leave a comment:
Leave a comment: