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[Qemu-devel] Re: [PATCH][block] qcow2: Support exact L1 table growth
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] Re: [PATCH][block] qcow2: Support exact L1 table growth |
Date: |
Tue, 19 Oct 2010 18:15:11 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.0.7-1.fc12 Thunderbird/3.0.7 |
Am 18.10.2010 17:53, schrieb Stefan Hajnoczi:
> The L1 table grow operation includes a size calculation that bumps up
> the new L1 table size in order to anticipate the size needs of vmstate
> data. This helps reduce the number of times that the L1 table has to be
> grown when vmstate data is appended.
>
> This size overhead is not necessary during image creation,
> bdrv_truncate(), or snapshot goto operations. In fact, existing
> qemu-iotests that exercise table growth are no longer able to trigger it
> because image creation preallocates an L1 table that is too large after
> changes to qcow_create2().
>
> This patch keeps the size calculation but also adds exact growth for
> callers that do not want to inflate the L1 table size unnecessarily.
>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
Thanks, applied to the block branch.
Kevin