linux-kernel - cputime takes cstate into consideration

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Message-ID: <CANRm+Cyge6viybs63pt7W-cRdntx+wfyOq5EWE2qmEQ71SzMHg@mail.gmail.com>
Date:   Wed, 26 Jun 2019 17:43:55 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krcmar <rkrcmar@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        KarimAllah <karahmed@...zon.de>,
        LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>
Subject: cputime takes cstate into consideration

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?

Regards,
Wanpeng Li