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Re: [Qemu-devel] [PATCH 00/23] block migration: Fixes, cleanups and spee

From: Pierre Riteau
Subject: Re: [Qemu-devel] [PATCH 00/23] block migration: Fixes, cleanups and speedups
Date: Mon, 30 Nov 2009 20:23:47 +0100

On 30 nov. 2009, at 19:50, Pierre Riteau wrote:

> I'm currently testing these patches. Here are a few issues I noticed, before 
> I forget about them.
> - "migrate -d -b tcp:dest:port" works, but "migrate -b -d tcp:dest:port" 
> doesn't, although "help migrate" doesn't really specify ordering as 
> important. But anyway I think Liran is working on a new version of the 
> command.
> - We use bdrv_aio_readv() to read blocks from the disk. This function 
> increments rd_bytes and rd_ops, which are reported by "info blockstats". I 
> don't think this read operations should appear in VM activity, especially if 
> this interface is used by libvirt to report VM stats (and draw graphs in 
> virt-manager, etc.). Same for write stats.
> - We may need to call bdrv_reset_dirty() _before_ sending the data, to be 
> sure the block is not rewritten in the meantime (maybe it's an issue only 
> with kvm?)
> - I seem to remember that disk images with 0 size are now possible. I'm 
> afraid we will hit a divide by zero in this case: "progress = 
> completed_sector_sum * 100 / block_mig_state.total_sector_sum;"
> Apart from that, it works quite fine. Still a few things to cleanup (e.g. 
> unused constants) but much better than before.
> However, I haven't tested the incremental transfer support at all yet. It's 
> on my todo list.

BTW, of these four issues, only the last one is related to Jan changes. The 
others were there before.
This is for saying that I strongly agree with the patch series.

Pierre Riteau -- http://perso.univ-rennes1.fr/pierre.riteau/

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