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[Qemu-devel] [Bug 524447] Re: virsh save is very slow
From: |
Anthony Liguori |
Subject: |
[Qemu-devel] [Bug 524447] Re: virsh save is very slow |
Date: |
Wed, 02 Jun 2010 16:16:44 -0000 |
This actually turns out to be related to dd's default block size. By
default, dd uses a block size of 512. The effect of this is that qemu
fills the pipe buffer very quickly because dd just is submitting very
small requests (that will require a RMW).
If you set an explict block size with dd (via bs=1M), you'll notice a
significant improvement in throughput.
So I think this turns out to be a libvirt issue, not a qemu issue.
** Changed in: qemu
Status: Confirmed => Invalid
--
virsh save is very slow
https://bugs.launchpad.net/bugs/524447
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Status in QEMU: Invalid
Status in “qemu-kvm” package in Ubuntu: Confirmed
Bug description:
As reported here:
http://www.redhat.com/archives/libvir-list/2009-December/msg00203.html
"virsh save" is very slow - it writes the image at around 1MB/sec on my test
system.
(I think I saw a bug report for this issue on Fedora's bugzilla, but I can't
find it now...)
Confirmed under Karmic.
- [Qemu-devel] [Bug 524447] Re: virsh save is very slow, Anthony Liguori, 2010/06/02
- [Qemu-devel] [Bug 524447] Re: virsh save is very slow,
Anthony Liguori <=
- [Qemu-devel] [Bug 524447] Re: virsh save is very slow, Cole Robinson, 2010/06/02
- [Qemu-devel] [Bug 524447] Re: virsh save is very slow, Dave Walker, 2010/06/14
- [Qemu-devel] [Bug 524447] Re: virsh save is very slow, Dave Walker, 2010/06/14
- [Qemu-devel] [Bug 524447] Re: virsh save is very slow, Chris Bainbridge, 2010/06/15
- [Qemu-devel] [Bug 524447] Re: virsh save is very slow, Serge Hallyn, 2010/06/22