From: Marcelo Tosatti <mtosatti@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
"Wanpeng Li" <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Linux PM" <linux-pm@vger.kernel.org>
Subject: Re: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available
Date: Sat, 3 Aug 2019 17:21:01 -0300 [thread overview]
Message-ID: <20190803202058.GA9316@amt.cnet> (raw)
In-Reply-To: <c3fe182f-627f-88ad-cb4d-a4189202b438@redhat.com>
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@tencent.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@intel.com>
> >> Cc: Paolo Bonzini <pbonzini@redhat.com>
> >> Cc: Radim Krčmář <rkrcmar@redhat.com>
> >> Cc: Marcelo Tosatti <mtosatti@redhat.com>
> >> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> >
> > Paolo, Marcelo, any comments?
>
> Yes, it's a good idea.
>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
>
> Paolo
I think KVM_HINTS_REALTIME is being abused somewhat.
It has no clear meaning and used in different locations
for different purposes.
For example, i think that using pv queued spinlocks and
haltpoll is a desired scenario, which the patch below disallows.
Wanpeng Li, currently the driver does not autoload. So polling in
the guest has to be enabled manually. Isnt that sufficient?
next prev parent reply other threads:[~2019-08-03 20:21 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1564643196-7797-1-git-send-email-wanpengli@tencent.com>
2019-08-01 16:51 ` [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available Rafael J. Wysocki
2019-08-01 16:54 ` Paolo Bonzini
2019-08-03 20:21 ` Marcelo Tosatti [this message]
2019-08-13 0:55 ` Wanpeng Li
2019-08-13 7:55 ` Paolo Bonzini
2019-08-26 20:40 ` Marcelo Tosatti
2019-08-27 0:43 ` Wanpeng Li
2019-08-28 8:35 ` Wanpeng Li
2019-08-28 8:45 ` Rafael J. Wysocki
2019-08-28 8:48 ` Wanpeng Li
2019-08-28 14:39 ` Marcelo Tosatti
2019-08-28 23:37 ` Rafael J. Wysocki
2019-08-29 12:04 ` Marcelo Tosatti
2019-08-29 12:16 ` Wanpeng Li
2019-08-29 12:53 ` Marcelo Tosatti
2019-08-29 14:39 ` Marcelo Tosatti
2019-08-28 14:48 ` Marcelo Tosatti
2019-08-28 14:52 ` Marcelo Tosatti
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