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Re: [PATCH] iotests/055: Use cache.no-flush for vmdk target


From: Eric Blake
Subject: Re: [PATCH] iotests/055: Use cache.no-flush for vmdk target
Date: Tue, 5 May 2020 09:02:51 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0

On 5/5/20 1:46 AM, Kevin Wolf wrote:
055 uses the backup block job to create a compressed backup of an
$IMGFMT image with both qcow2 and vmdk targets. However, cluster
allocation in vmdk is very slow because it flushes the image file after
each L2 update.

There is no reason why we need this level of safety in this test, so
let's disable flushes for vmdk. For the blockdev-backup tests this is
achieved by simply adding the cache.no-flush=on to the drive_add() for
the target. For drive-backup, the caching flags are copied from the
source node, so we'll also add the flag to the source node, even though
it is not vmdk.

This can make the test run significantly faster (though it doesn't make
a difference on tmpfs). In my usual setup it goes from ~45s to ~15s.

Signed-off-by: Kevin Wolf <address@hidden>
---
  tests/qemu-iotests/055 | 11 +++++++----
  1 file changed, 7 insertions(+), 4 deletions(-)

Reviewed-by: Eric Blake <address@hidden>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org




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