linux-kernel - Re: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available

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Message-ID: <CANRm+CxqYMzgvxYyhZLmEzYd6SLTyHdRzKVaSiHO-4SV+OwZUQ@mail.gmail.com>
Date:   Wed, 28 Aug 2019 16:35:30 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Marcelo Tosatti <mtosatti@...hat.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated
 physical CPUs are available

On Tue, 27 Aug 2019 at 08:43, Wanpeng Li <kernellwp@...il.com> wrote:
>
> Cc Michael S. Tsirkin,
> On Tue, 27 Aug 2019 at 04:42, Marcelo Tosatti <mtosatti@...hat.com> wrote:
> >
> > On Tue, Aug 13, 2019 at 08:55:29AM +0800, Wanpeng Li wrote:
> > > On Sun, 4 Aug 2019 at 04:21, Marcelo Tosatti <mtosatti@...hat.com> wrote:
> > > >
> > > > On Thu, Aug 01, 2019 at 06:54:49PM +0200, Paolo Bonzini wrote:
> > > > > On 01/08/19 18:51, Rafael J. Wysocki wrote:
> > > > > > On 8/1/2019 9:06 AM, Wanpeng Li wrote:
> > > > > >> From: Wanpeng Li <wanpengli@...cent.com>
> > > > > >>
> > > > > >> The downside of guest side polling is that polling is performed even
> > > > > >> with other runnable tasks in the host. However, even if poll in kvm
> > > > > >> can aware whether or not other runnable tasks in the same pCPU, it
> > > > > >> can still incur extra overhead in over-subscribe scenario. Now we can
> > > > > >> just enable guest polling when dedicated pCPUs are available.
> > > > > >>
> > > > > >> Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > > > > >> Cc: Paolo Bonzini <pbonzini@...hat.com>
> > > > > >> Cc: Radim Krčmář <rkrcmar@...hat.com>
> > > > > >> Cc: Marcelo Tosatti <mtosatti@...hat.com>
> > > > > >> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> > > > > >
> > > > > > Paolo, Marcelo, any comments?
> > > > >
> > > > > Yes, it's a good idea.
> > > > >
> > > > > Acked-by: Paolo Bonzini <pbonzini@...hat.com>

Hi Marcelo,

If you don't have more concern, I guess Rafael can apply this patch
now since the merge window is not too far.

Regards,
Wanpeng Li