From: Paolo Bonzini <pbonzini@redhat.com>
To: Arthur Chunqi Li <yzt356@gmail.com>
Cc: kvm <kvm@vger.kernel.org>, Jan Kiszka <jan.kiszka@web.de>
Subject: Re: About preemption timer
Date: Tue, 17 Dec 2013 12:22:08 +0100 [thread overview]
Message-ID: <52B033E0.1010605@redhat.com> (raw)
In-Reply-To: <CABpY8M+p5MpgOg4Ggd_Of-YuybwFEeBXKuYrioBzV72pK1H31w@mail.gmail.com>
Il 17/12/2013 10:32, Arthur Chunqi Li ha scritto:
> Hi Jan and Paolo,
>
> I've tried to use preemption timer in KVM to trap vcpu regularly, but
> there's something unexpected. I run a VM with 4 vcpus and give them
> the same preemption timer value (e.g. 1000000) with all bits set
> (activate/save bits), then reset the value in preemption time-out
> handler.
>
> Thus I expected these vcpus trap regularly in some special turns. But
> I found that when the VM is not busy, some vcpus are trapped much less
> frequently than others. In Intel SDM, I noticed that preemption timer
> is only related to TSC, and I think all the vcpus should trap in a
> similar frequency.
Does the preemption timer testcase pass on your machine? The preemption
timer is known to have bugs.
Paolo
prev parent reply other threads:[~2013-12-17 11:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-17 9:32 About preemption timer Arthur Chunqi Li
2013-12-17 11:21 ` Jan Kiszka
2013-12-17 11:31 ` Arthur Chunqi Li
2013-12-17 12:43 ` Jan Kiszka
2013-12-17 12:59 ` Arthur Chunqi Li
2013-12-17 15:17 ` Jan Kiszka
2013-12-18 3:27 ` R
2013-12-18 6:58 ` Jan Kiszka
2013-12-17 11:22 ` Paolo Bonzini [this message]
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