From: Avi Kivity <avi@redhat.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: "Zhai, Edwin" <edwin.zhai@intel.com>, Ingo Molnar <mingo@elte.hu>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH] [RESEND] KVM:VMX: Add support for Pause-Loop Exiting
Date: Sun, 27 Sep 2009 15:47:55 +0200 [thread overview]
Message-ID: <4ABF6D0B.8080603@redhat.com> (raw)
In-Reply-To: <20090927134650.GC29634@8bytes.org>
On 09/27/2009 03:46 PM, Joerg Roedel wrote:
>
>> We can't find exactly which vcpu, but we can:
>>
>> - rule out threads that are not vcpus for this guest
>> - rule out threads that are already running
>>
>> A major problem with sleep() is that it effectively reduces the vm
>> priority relative to guests that don't have spinlock contention. By
>> selecting a random nonrunnable vcpu belonging to this guest, we at least
>> preserve the guest's timeslice.
>>
> Ok, that makes sense. But before trying that we should probably try to
> call just yield() instead of schedule()? I remember someone from our
> team here at AMD did this for Xen a while ago and already had pretty
> good results with that. Xen has a completly other scheduler but maybe
> its worth trying?
>
yield() is a no-op in CFS.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2009-09-27 13:48 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-23 14:04 [PATCH] [RESEND] KVM:VMX: Add support for Pause-Loop Exiting Zhai, Edwin
2009-09-23 14:09 ` Avi Kivity
2009-09-25 1:11 ` Zhai, Edwin
2009-09-27 8:28 ` Avi Kivity
2009-09-28 9:33 ` Zhai, Edwin
2009-09-29 12:05 ` Zhai, Edwin
2009-09-29 13:34 ` Avi Kivity
2009-09-30 1:01 ` Zhai, Edwin
2009-09-30 6:28 ` Avi Kivity
2009-09-30 16:22 ` Marcelo Tosatti
2009-10-02 18:28 ` Marcelo Tosatti
2009-10-09 10:03 ` Zhai, Edwin
2009-10-11 15:34 ` Avi Kivity
2009-10-12 19:13 ` Marcelo Tosatti
2009-09-25 20:43 ` Joerg Roedel
2009-09-27 8:31 ` Avi Kivity
2009-09-27 13:46 ` Joerg Roedel
2009-09-27 13:47 ` Avi Kivity [this message]
2009-09-27 14:07 ` Joerg Roedel
2009-09-27 14:18 ` Avi Kivity
2009-09-27 14:53 ` Joerg Roedel
2009-09-29 16:46 ` Avi Kivity
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