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From: | Anthony Liguori |
Subject: | Re: [Qemu-devel] [PATCH] QEMU: change default disk cache behavior |
Date: | Thu, 20 May 2010 07:30:28 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Lightning/1.0pre Thunderbird/3.0 |
On 05/20/2010 04:32 AM, address@hidden wrote:
From: Jes Sorensen<address@hidden> We seem to get into the discussion of what is the correct default setting disk images in QEMU. The libvirt team is reluctant to change specified for newly created images without the default setting matching it, and everybody seems to agree that the current setting of WT is the worse possible option. 'nocache' seems to be the preferred option, but it doesn't work for all cases, like images on ramfs, NFS etc. Therefore, here is a patch that does two things: - default to "nocache" - in case of failure with nocache, retry with "write-back"
This sort of change requires performance data in a variety of circumstances to justify.
And I strongly suspect that such a blanket change would be wrong but that a more targeted change like making cache=none default for physical devices would satisfy mostly everyone.
Regards, Anthony Liguori
Jes Sorensen (1): QEMU: Change default disk caching to nocache vl.c | 25 +++++++++++++++++++------ 1 files changed, 19 insertions(+), 6 deletions(-)
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