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Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver
From: |
Dietmar Maurer |
Subject: |
Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver |
Date: |
Thu, 21 Feb 2013 15:25:21 +0000 |
> > I just posted v5 of the patch. But I get a slow down of 15% if I use
> > bdrv_is_allocated_above. (tested with empty qcow2 files.)
>
> Strange, for an unallocated area bdrv_is_allocated_above and bdrv_read really
> do the same thing apart from writing the zeroes to the buffer.
> The code looks okay, does a profile say where the time is being spent?
> Or does the is_allocated_above ever trigger (are you using metadata
> preallocation)?
Yes, I use metadata preallocation. But that does not explain why it gets slower?
> BTW, any reason why BACKUP_BLOCKS_PER_CLUSTER is hardcoded and you're
> not using the cluster size from bdrv_get_info?
A backup includes several block devices, and I want to have the same cluster
size
for all. It makes the code easier.
- [Qemu-devel] [PATCH v3 4/6] introduce new vma archive format, (continued)
- [Qemu-devel] [PATCH v3 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/19
- [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/19
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Eric Blake, 2013/02/19
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Paolo Bonzini, 2013/02/20
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Paolo Bonzini, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Paolo Bonzini, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver,
Dietmar Maurer <=
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Paolo Bonzini, 2013/02/21
Re: [Qemu-devel] [PATCH v3 1/6] RFC: Efficient VM backup for qemu, Eric Blake, 2013/02/19
Re: [Qemu-devel] [PATCH v3 1/6] RFC: Efficient VM backup for qemu, Dietmar Maurer, 2013/02/20