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| From: | Avi Kivity |
| Subject: | Re: [Qemu-devel] Re: How can I understand CONFIG_IO_THREAD ? |
| Date: | Mon, 21 Feb 2011 11:29:49 +0200 |
| User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101209 Fedora/3.1.7-0.35.b3pre.fc14 Thunderbird/3.1.7 |
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.
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