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[Qemu-devel] [Bug 1751264] Re: qemu-img convert issue in a tmpfs partiti
From: |
Teddy VALETTE |
Subject: |
[Qemu-devel] [Bug 1751264] Re: qemu-img convert issue in a tmpfs partition |
Date: |
Mon, 26 Feb 2018 13:28:23 -0000 |
** Description changed:
qemu-img convert command is slow when the file to convert is located in
a tmpfs formatted partition.
v2.1.0 on debian/jessie x64, ext4: 10m14s
v2.1.0 on debian/jessie x64, tmpfs: 10m15s
v2.1.0 on debian/stretch x64, ext4: 11m9s
v2.1.0 on debian/stretch x64, tmpfs: 10m21.362s
v2.8.0 on debian/jessie x64, ext4: 10m21s
- v2.8.0 on debian/jessie x64, tmpfs: Too long
+ v2.8.0 on debian/jessie x64, tmpfs: Too long (50min+)
v2.8.0 on debian/stretch x64, ext4: 10m42s
- v2.8.0 on debian/stretch x64, tmpfs: Too long
+ v2.8.0 on debian/stretch x64, tmpfs: Too long (50min+)
It seems that the issue is caused by this commit :
https://github.com/qemu/qemu/commit/690c7301600162421b928c7f26fd488fd8fa464e
In order to reproduce this bug :
1/ mount a tmpfs partition : mount -t tmpfs tmpfs /tmp
2/ get a vmdk file (we used a 15GB image) and put it on /tmp
3/ run the 'qemu-img convert -O qcow2 /tmp/file.vmdk /path/to/destination'
command
When we trace the process, we can see that there's a lseek loop which is
very slow (compare to outside a tmpfs partition).
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https://bugs.launchpad.net/bugs/1751264
Title:
qemu-img convert issue in a tmpfs partition
Status in QEMU:
New
Bug description:
qemu-img convert command is slow when the file to convert is located
in a tmpfs formatted partition.
v2.1.0 on debian/jessie x64, ext4: 10m14s
v2.1.0 on debian/jessie x64, tmpfs: 10m15s
v2.1.0 on debian/stretch x64, ext4: 11m9s
v2.1.0 on debian/stretch x64, tmpfs: 10m21.362s
v2.8.0 on debian/jessie x64, ext4: 10m21s
v2.8.0 on debian/jessie x64, tmpfs: Too long (50min+)
v2.8.0 on debian/stretch x64, ext4: 10m42s
v2.8.0 on debian/stretch x64, tmpfs: Too long (50min+)
It seems that the issue is caused by this commit :
https://github.com/qemu/qemu/commit/690c7301600162421b928c7f26fd488fd8fa464e
In order to reproduce this bug :
1/ mount a tmpfs partition : mount -t tmpfs tmpfs /tmp
2/ get a vmdk file (we used a 15GB image) and put it on /tmp
3/ run the 'qemu-img convert -O qcow2 /tmp/file.vmdk /path/to/destination'
command
When we trace the process, we can see that there's a lseek loop which
is very slow (compare to outside a tmpfs partition).
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