PG: GPU bandwidth

alpha754293 · Post by **alpha754293** » Mon Apr 13, 2009 12:29 am

How much of the 4-8 GB/s bandwidth (depend on PCIe version) does the GPU client actually use? 100%? 50%? ??

P5-133XL · Post by **P5-133XL** » Mon Apr 13, 2009 12:52 am

People can fold on 2x PCI-e without much PPD penalty. So the answer is very little.

alpha754293 · Post by **alpha754293** » Mon Apr 13, 2009 12:53 am

P5-133XL wrote:People can fold on 2x PCI-e without much PPD penalty. So the answer is very little.

Excellent. Good to know. Thanks.

Slash_2CPU · Post by **Slash_2CPU** » Mon Apr 13, 2009 1:38 am

2x version 1.1 PCIe incurs a small decrease.

2x PCIe 2.0 is twice as fast, and has no loss at all. Same for 4x PCIe 1.1.

alpha754293 · Post by **alpha754293** » Mon Apr 13, 2009 1:44 am

Slash_2CPU wrote:2x version 1.1 PCIe incurs a small decrease.

2x PCIe 2.0 is twice as fast, and has no loss at all. Same for 4x PCIe 1.1.

That doesn't make sense. The PCIe 1.0 Spec calls for 250 MB/s (2 Gb/s) per lane, while PCIe 2.0 calls for 500 MB/s (4 Gb/s) per lane. hmmm...

7im · Post by **7im** » Mon Apr 13, 2009 5:45 am

Total bandwidth is obviously not the only gating factor in the older spec.

alpha754293 · Post by **alpha754293** » Mon Apr 13, 2009 9:19 am

7im wrote:Total bandwidth is obviously not the only gating factor in the older spec.

Depends on which metric you're talking about.

7im · Post by **7im** » Thu Apr 16, 2009 5:27 am

All of them except bandwidth, what else?

alpha754293 · Post by **alpha754293** » Thu Apr 16, 2009 5:41 am

7im wrote:All of them except bandwidth, what else?

But I think either all or almost all of the other gating factors affects the bandwidth, so...

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