[HN Gopher] Microbenchmarking Intel's Arc A770
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Microbenchmarking Intel's Arc A770
Author : pantalaimon
Score : 85 points
Date : 2022-10-20 13:28 UTC (9 hours ago)
(HTM) web link (chipsandcheese.com)
(TXT) w3m dump (chipsandcheese.com)
| timw4mail wrote:
| I'm kind of disappointed all the tests were without ReBAR. I'm
| curious as to what kind of difference that makes.
| onli wrote:
| You are probably aware, but ReBAR has a huge effect on these
| card, so much that it is a requirement to get stable and
| acceptable FPS in games. I would assume that means the effect
| would be huge also in those smaller benchmarks.
|
| _edit:_ But was it really off in general, or only for the
| PCI-e 3.0 part of the article?
| wtallis wrote:
| ReBAR only matters for transfers across the PCIe link, so for
| most of the tests in the article it's completely irrelevant.
| And even for the PCIe transfer tests, ReBAR should only
| affect the portions of the tests that are accessing more GPU
| memory than the default BAR size used for 32-bit
| compatibility.
| timw4mail wrote:
| Considering how much the Arc series loves to share system
| memory, I'm not so sure.
| wtallis wrote:
| Intel's having to find and fix every place their drivers
| assumed that the CPU's RAM and the GPU's RAM were the
| same pool of memory. As a result, it's completely
| unsurprising that they're struggling with performance in
| real applications and games, but it doesn't provide a
| reason to expect microbenchmarks such as these to run
| afoul of an irrelevant problem.
| ErneX wrote:
| These GPUs practically require ReBAR, performance without it
| drops significantly.
| clamchowder wrote:
| Apologies for the confusion, the tests were run with ReBAR.
| I've updated the article to reflect that
|
| Shouldn't affect the conclusion for anything besides the PCIe
| copy to/from GPU tests.
| TomVDB wrote:
| It would make zero difference, except, maybe, for the PCIe
| bandwidth test. Because all other tests were stressed
| interfaces that reside within the GPU silicon itself or between
| the GPU and the DRAM.
|
| Even the numbers of PCIe bandwidth test might not change much,
| even it's trying to test medium size memory to memory block
| transfers.
| atlgator wrote:
| I would love to get my hands on one. They seem to be sold out
| everywhere.
| MegaDeKay wrote:
| If on Windows, you might want to check out the Gamers Nexus
| reviews on YouTube: the Intel drivers are a dumpster fire and
| build quality is... not great.
|
| https://www.youtube.com/c/GamersNexus/videos
| DRAGONERO wrote:
| Is the benchmark suite available somewhere?
| clamchowder wrote:
| (Author here) See
| https://github.com/clamchowder/Microbenchmarks/tree/master/G...
|
| It's very much a work in progress, as noted in the article. And
| some of the stuff that worked reasonably well on my cards, like
| the instruction rate test when trying to measure throughput
| across the entire card, went down the drain when run on Arc.
| jra101 wrote:
| Have you tried reducing the register count in your FP32 FMA
| test by increasing the iteration count and reducing the
| number of values computed per loop?
|
| Instead of computing 8 independent values, compute one with
| 8x more iterations: for (int i = 0; i <
| count * 8; i++) { v0 += acc * v0; }
|
| That plus inlining the iteration count so the compiler can
| unroll the loop might help get closer to SOL.
| clamchowder wrote:
| The problem is loop overhead matters on AMD, because AMD's
| compiler doesn't unroll the loop. Nvidia's does, so it
| doesn't matter for them.
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(page generated 2022-10-20 23:01 UTC)