From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Zhanghaoyu (A)" <haoyu.zhang@huawei.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
KVM <kvm@vger.kernel.org>, Gleb Natapov <gleb@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Luonengjun <luonengjun@huawei.com>,
"Huangweidong (C)" <weidong.huang@huawei.com>
Subject: Re: question about VM kernel parameter idle=<poll/mwait/halt/nomwait>
Date: Thu, 21 Nov 2013 09:01:39 +0200 [thread overview]
Message-ID: <20131121070139.GL19005@redhat.com> (raw)
In-Reply-To: <D3E216785288A145B7BC975F83A2ED10448A949B@SZXEMA510-MBS.china.huawei.com>
On Thu, Nov 21, 2013 at 03:45:28AM +0000, Zhanghaoyu (A) wrote:
> Hi, all
>
> What's the difference of the linux guest kernel parameter idle=<poll/mwait/halt/nomwait>, especially in performance?
>
> Taking the performance into account, which one is best?
>
> In my opinion, if the number of all VMs' vcpus is far more than that of pcpus, e.g. SPECVirt test, idle=halt is better for server's total throughput,
> otherwise, e.g. in some CT scenario, the number of total vcpus is not greater than that of pcpus, idle=poll is better for server's total throughput,
> because of less latency and VMEXIT.
Makes sense overall.
> linux-3.9 and above, idle=mwait is not recommended.
>
> Thanks,
> Zhang Haoyu
Does it actually have effect? I didn't think it would.
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Zhanghaoyu (A)" <haoyu.zhang@huawei.com>
Cc: "Huangweidong (C)" <weidong.huang@huawei.com>,
KVM <kvm@vger.kernel.org>, Gleb Natapov <gleb@redhat.com>,
Luonengjun <luonengjun@huawei.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] question about VM kernel parameter idle=<poll/mwait/halt/nomwait>
Date: Thu, 21 Nov 2013 09:01:39 +0200 [thread overview]
Message-ID: <20131121070139.GL19005@redhat.com> (raw)
In-Reply-To: <D3E216785288A145B7BC975F83A2ED10448A949B@SZXEMA510-MBS.china.huawei.com>
On Thu, Nov 21, 2013 at 03:45:28AM +0000, Zhanghaoyu (A) wrote:
> Hi, all
>
> What's the difference of the linux guest kernel parameter idle=<poll/mwait/halt/nomwait>, especially in performance?
>
> Taking the performance into account, which one is best?
>
> In my opinion, if the number of all VMs' vcpus is far more than that of pcpus, e.g. SPECVirt test, idle=halt is better for server's total throughput,
> otherwise, e.g. in some CT scenario, the number of total vcpus is not greater than that of pcpus, idle=poll is better for server's total throughput,
> because of less latency and VMEXIT.
Makes sense overall.
> linux-3.9 and above, idle=mwait is not recommended.
>
> Thanks,
> Zhang Haoyu
Does it actually have effect? I didn't think it would.
next prev parent reply other threads:[~2013-11-21 6:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-21 3:45 question about VM kernel parameter idle=<poll/mwait/halt/nomwait> Zhanghaoyu (A)
2013-11-21 3:45 ` [Qemu-devel] " Zhanghaoyu (A)
2013-11-21 7:01 ` Michael S. Tsirkin [this message]
2013-11-21 7:01 ` Michael S. Tsirkin
2013-11-21 7:22 ` Gleb Natapov
2013-11-21 7:22 ` [Qemu-devel] " Gleb Natapov
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