From: Peter Zijlstra <peterz@infradead.org>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Paolo Bonzini <pbonzini@redhat.com>,
Radim Krcmar <rkrcmar@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
KarimAllah <karahmed@amazon.de>,
LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>
Subject: Re: cputime takes cstate into consideration
Date: Wed, 26 Jun 2019 12:13:20 +0200 [thread overview]
Message-ID: <20190626101320.GX3402@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CANRm+Cyge6viybs63pt7W-cRdntx+wfyOq5EWE2qmEQ71SzMHg@mail.gmail.com>
On Wed, Jun 26, 2019 at 05:43:55PM +0800, Wanpeng Li wrote:
> Hi all,
>
> After exposing mwait/monitor into kvm guest, the guest can make
> physical cpu enter deeper cstate through mwait instruction, however,
> the top command on host still observe 100% cpu utilization since qemu
> process is running even though guest who has the power management
> capability executes mwait. Actually we can observe the physical cpu
> has already enter deeper cstate by powertop on host. Could we take
> cstate into consideration when accounting cputime etc?
Either we account runtime on the CPU itself, in which case it will not
be in a C state due to actually running an interrupt that does
accounting, or we do it remote (NOHZ_FULL case) and there is no way to
know what C state, if any, that CPU is in.
next prev parent reply other threads:[~2019-06-26 10:13 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-26 9:43 cputime takes cstate into consideration Wanpeng Li
2019-06-26 10:13 ` Peter Zijlstra [this message]
2019-06-26 10:33 ` Thomas Gleixner
2019-06-26 14:54 ` Konrad Rzeszutek Wilk
2019-06-26 16:16 ` Peter Zijlstra
2019-06-26 18:30 ` Konrad Rzeszutek Wilk
2019-06-26 18:41 ` Thomas Gleixner
2019-06-26 18:55 ` Raslan, KarimAllah
2019-06-26 19:19 ` Thomas Gleixner
2019-06-26 19:21 ` Peter Zijlstra
2019-06-26 19:27 ` Raslan, KarimAllah
2019-06-26 19:32 ` Thomas Gleixner
2019-06-26 20:01 ` Peter Zijlstra
2019-06-26 20:09 ` Thomas Gleixner
2019-12-10 0:44 ` Wanpeng Li
2019-06-26 19:29 ` Thomas Gleixner
2019-06-26 18:58 ` Raslan, KarimAllah
2019-06-26 19:23 ` Thomas Gleixner
2019-07-09 2:00 ` Ankur Arora
2019-07-09 2:06 ` Wanpeng Li
2019-07-09 12:38 ` Peter Zijlstra
2019-07-09 18:27 ` Ankur Arora
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