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From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>, Wanpeng Li <kernellwp@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	KarimAllah <karahmed@amazon.de>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Ingo Molnar <mingo@kernel.org>,
	Ankur Arora <ankur.a.arora@oracle.com>,
	christopher.s.hall@intel.com, hubert.chrzaniuk@intel.com,
	len.brown@intel.com, thomas.lendacky@amd.com, rjw@rjwysocki.net
Subject: Re: [PATCH RFC] sched/fair: Penalty the cfs task which executes mwait/hlt
Date: Mon, 13 Jan 2020 12:52:20 +0100	[thread overview]
Message-ID: <ee2b6da2-be8c-2540-29e9-ffbb9fdfd3fc@redhat.com> (raw)
In-Reply-To: <20200113104314.GU2844@hirez.programming.kicks-ass.net>

On 13/01/20 11:43, Peter Zijlstra wrote:
> So the very first thing we need to get sorted is that MPERF/TSC ratio
> thing. TurboStat does it, but has 'funny' hacks on like:
> 
>   b2b34dfe4d9a ("tools/power turbostat: KNL workaround for %Busy and Avg_MHz")
> 
> and I imagine that there's going to be more exceptions there. You're
> basically going to have to get both Intel and AMD to commit to this.
> 
> IFF we can get concensus on MPERF/TSC, then yes, that is a reasonable
> way to detect a VCPU being idle I suppose. I've added a bunch of people
> who seem to know about this.
> 
> Anyone, what will it take to get MPERF/TSC 'working' ?

Do we really need MPERF/TSC for this use case, or can we just track
APERF as well and do MPERF/APERF to compute the "non-idle" time?

Paolo


  parent reply	other threads:[~2020-01-13 11:52 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-08  1:50 [PATCH RFC] sched/fair: Penalty the cfs task which executes mwait/hlt Wanpeng Li
2020-01-08 15:50 ` Peter Zijlstra
2020-01-08 17:14   ` Paolo Bonzini
2020-01-09 11:53     ` Wanpeng Li
2020-01-13 10:43       ` Peter Zijlstra
2020-01-13 11:18         ` Rafael J. Wysocki
2020-01-13 12:29           ` Peter Zijlstra
2020-01-14 22:46             ` Rafael J. Wysocki
2020-01-13 11:52         ` Paolo Bonzini [this message]
2020-01-13 12:35           ` Peter Zijlstra
2020-01-14 10:53             ` Wanpeng Li

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