* Rik van Riel <riel@xxxxxxxxxx> wrote:
> Performance measurements will show us how much of an impact it
> makes, since I don't think we have never done apples to apples
> comparisons with just this thing toggled :)
I've done a couple of quick measurements to characterise it: as
expected this patch simply does not matter much when THP is
enabled - and most testers I worked with had THP enabled.
Testing with THP off hurst most NUMA workloads dearly and tells
very little about the real NUMA story of these workloads. If you
turn off THP you are living with a constant ~25% regression -
just check the THP and no-THP numbers I posted:
[ 32-warehouse SPECjbb test benchmarks ]
mainline: 395 k/sec
mainline +THP: 524 k/sec
numa/core +patch: 512 k/sec [ +29.6% ]
numa/core +patch +THP: 654 k/sec [ +24.8% ]
The group of testers who had THP disabled was thus very low -
maybe only Mel alone? The testers I worked with all had THP
enabled.
I'd encourage everyone to report unusual 'tweaks' done before
tests are reported - no matter how well intended the purpose of
that tweak. There's just so many config variations we can test
and we obviously check the most logically and most scalably
configured system variants first.
Thanks,
Ingo
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