From: Avi Kivity <avi@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: wang sheng <wansheg@gmail.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: How can I understand CONFIG_IO_THREAD ?
Date: Mon, 21 Feb 2011 11:29:49 +0200 [thread overview]
Message-ID: <4D62308D.1070101@redhat.com> (raw)
In-Reply-To: <4D621F77.3080802@redhat.com>
On 02/21/2011 10:16 AM, Paolo Bonzini wrote:
> On 02/21/2011 04:13 AM, wang sheng wrote:
>> What is the purpose of io_thread desigment in qemu ?
>
> There was a lengthy thread recently explaining how it helps fixing a
> possibly delay in handling I/O. It is also useful for KVM, where you
> have one I/O thread and multiple CPU threads. This way, KVM can
> implement "real" SMP (i.e. multiple virtual CPUs running concurrently).
>
In fact kvm smp was available even before the iothread; one thread
handled both vcpu 0 and I/O completions, while the other threads only
handled a vcpu each. Later, the first thread was split into an iothread
and a vcpu 0 thread.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
prev parent reply other threads:[~2011-02-21 9:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-21 3:13 [Qemu-devel] How can I understand CONFIG_IO_THREAD ? wang sheng
2011-02-21 8:16 ` [Qemu-devel] " Paolo Bonzini
2011-02-21 9:29 ` Avi Kivity [this message]
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