From: Stefan Hajnoczi <stefanha@gmail.com>
To: 陳韋任 <chenwj@iis.sinica.edu.tw>
Cc: qemu-devel <qemu-devel@nongnu.org>, Xin Tong <xerox.time.tech@gmail.com>
Subject: Re: [Qemu-devel] multiprocessor on kvm
Date: Tue, 8 Nov 2011 12:23:26 +0000 [thread overview]
Message-ID: <CAJSP0QWXL2k-xMvGz_85cnwDdSSzCLGai+mOmEpOLeszpxUHxw@mail.gmail.com> (raw)
In-Reply-To: <20111108121056.GA96832@cs.nctu.edu.tw>
On Tue, Nov 8, 2011 at 12:10 PM, 陳韋任 <chenwj@iis.sinica.edu.tw> wrote:
> On Tue, Nov 08, 2011 at 08:04:44PM +0800, 陳韋任 wrote:
>> > I am wondering that when one uses qemu with kvm. How many cores are
>> > exposed and available to the guest os ( assuming the host has 4 cores
>> > ). is this configurable ?
>>
>> QEMU provides "-smp" option, but those virtual cpus are scheduled in
>> round-robin fashion. In other words, it's not real parallelism. I don't
>> know if there is any difference with kvm enabled.
>
> IIRC, kvm uses QEMU for device emulation only. Those virtual cpus are
> ran on physical cpus simultaneously.
Right, qemu -enable-kvm will run a thread for each vCPU. So you get
true SMP parallelism.
QEMU without KVM mode, on the other hand, does round-robin scheduling
of vCPUs and does not take advantage of multiprocessor hosts.
Stefan
next prev parent reply other threads:[~2011-11-08 12:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-08 11:55 [Qemu-devel] multiprocessor on kvm Xin Tong
2011-11-08 12:04 ` 陳韋任
2011-11-08 12:10 ` 陳韋任
2011-11-08 12:23 ` Stefan Hajnoczi [this message]
2011-11-08 12:37 ` Xin Tong
2011-11-08 13:08 ` 陳韋任
2011-11-09 2:45 ` Dong Xu Wang
2011-11-09 2:50 ` 陳韋任
2011-11-08 14:21 ` Xin Tong
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