Messages in this thread | | | Date | Thu, 17 May 2018 12:59:07 +0200 | From | Juri Lelli <> | Subject | Re: [RFC/RFT] [PATCH 02/10] cpufreq: intel_pstate: Conditional frequency invariant accounting |
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On 16/05/18 18:31, Juri Lelli wrote: > On 16/05/18 17:47, Peter Zijlstra wrote: > > On Wed, May 16, 2018 at 05:19:25PM +0200, Juri Lelli wrote: > > > > > Anyway, FWIW I started testing this on a E5-2609 v3 and I'm not seeing > > > hackbench regressions so far (running with schedutil governor). > > > > https://en.wikipedia.org/wiki/Haswell_(microarchitecture)#Server_processors > > > > Lists the E5 2609 v3 as not having turbo at all, which is basically a > > best case scenario for this patch. > > > > As I wrote earlier today; when turbo exists, like say the 2699, then > > when we're busy we'll run at U=2.3/3.6 ~ .64, which might confuse > > things. > > Indeed. I was mostly trying to see if adding this to the tick might > introduce noticeable overhead.
Blindly testing on an i5-5200U (2.2/2.7 GHz) gave the following
# perf bench sched messaging --pipe --thread --group 2 --loop 20000
count mean std min 50% 95% 99% max hostname kernel i5-5200U test_after 30.0 13.843433 0.590605 12.369 13.810 14.85635 15.08205 15.127 test_before 30.0 13.571167 0.999798 12.228 13.302 15.57805 16.40029 16.690
It might be interesting to see what happens when using a single CPU only?
Also, I will look at how the util signals look when a single CPU is busy..
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