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Date:   Wed, 16 May 2018 18:31:05 +0200
From:   Juri Lelli <juri.lelli@redhat.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        tglx@linutronix.de, mingo@redhat.com, bp@suse.de, lenb@kernel.org,
        rjw@rjwysocki.net, mgorman@techsingularity.net, x86@kernel.org,
        linux-pm@vger.kernel.org, viresh.kumar@linaro.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC/RFT] [PATCH 02/10] cpufreq: intel_pstate: Conditional
 frequency invariant accounting
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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.