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From: | Udo Lembke |
Subject: | [Qemu-devel] Re: [PATCH 10/12] kvm: enable smp > 1 |
Date: | Wed, 19 May 2010 22:02:50 +0200 |
User-agent: | Mozilla-Thunderbird 2.0.0.24 (X11/20100329) |
Avi Kivity schrieb:
On 05/19/2010 12:57 PM, Udo Lembke wrote:Jan Kiszka schrieb:... --enable-io-thread? If you had it disabled, it would also answer my question if -smp works without problems without that feature. JanHi,i have a dumb question: what is the "--enable-io-thread"? Is this a kvm-switch?It's a ./configure switch for upstream qemu (don't use with qemu-kvm yet).My kvm 0.12.4 don't accept this switch. I'm know only "threads=n" as smp-parameter and "aio=threads" as drive-parameter.Because i look for a solution for a better io-performance of windows-guest with more than one cpu...Unrelated, what are your smp issues?
If i use one cpu i got a good io-performance: e.g. over 500MB/s at the profile "install" of the io-benchmark h2benchw.exe.( aio=threads | SAS-Raid-0 | ftp://ftp.heise.de/pub/ct/ctsi/h2benchw.zip | hwbenchw.exe -p -w iotest 0)
The same test but with two cpus gives results between 27 and 298 MB/s!Also in real life it's noticeable not only with an benchmark. I use a win-vm with two cpu for postscript-ripping and have a performance drop due to the bad io.
Udo
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