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Re: [Qemu-devel] [PATCH v5 7/7] Use qemu_put_buffer_async for guest memo


From: Paolo Bonzini
Subject: Re: [Qemu-devel] [PATCH v5 7/7] Use qemu_put_buffer_async for guest memory pages
Date: Fri, 05 Apr 2013 17:23:56 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4

Il 05/04/2013 15:44, Kevin Wolf ha scritto:
> This seems to have killed savevm performance. I noticed that
> qemu-iotests case 007 took forever on my test box (882 seconds instead
> of something like 10 seconds). It can be reproduced by this script:
> 
> export MALLOC_PERTURB_=11
> qemu-img create -f qcow2 -o compat=1.1 test.qcow2 1M
> time qemu-system-x86_64 -nographic -hda $TEST_IMG -serial none -monitor stdio 
> <<EOF
> savevm test
> quit
> EOF
> 
> This used to take about 0.6s for me, after this patch it's around 10s.

The solution could be to make bdrv_load_vmstate take an iov/iovcnt pair.

Alternatively, you can try the attached patch.  I haven't yet tested it
though, and won't be able to do so today.

Paolo

Attachment: savevm-performance.patch
Description: Text Data


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