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From: Kevin Wolf <kwolf@redhat.com>
To: Alex Bligh <alex@alex.org.uk>
Cc: qemu-devel@nongnu.org, stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH] Add delay option to blkdebug
Date: Mon, 1 Jul 2013 12:23:53 +0200	[thread overview]
Message-ID: <20130701102353.GB9000@dhcp-200-207.str.redhat.com> (raw)
In-Reply-To: <1372528923-12354-2-git-send-email-alex@alex.org.uk>

Am 29.06.2013 um 20:02 hat Alex Bligh geschrieben:
> Add a delay option to blkdebug, allowing operations to be delayed by
> a specifiable number of microseconds. Example configuration:
> 
> [inject-error]
> event = "read_aio"
> delay = "200000"
> 
> Signed-off-by: Alex Bligh <alex@alex.org.uk>

"inject-error" doesn't really describe this well. Shouldn't we rather
introduce a new section "[delay]" or something like that?

I remember that I once tried something similar, but never submitted it.
I think the reason was that using timers inside requests doesn't really
work. It works as long as everything is indeed asynchronous, but
bdrv_drain_all() or a loop waiting for a single request that tries to
make progress with qemu_aio_wait() will simply hang because timers
aren't processed in these nested event loops.

Kevin

  reply	other threads:[~2013-07-01 10:24 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-29 18:02 [Qemu-devel] [PATCH] [RFC] Add delay option to blkdebug Alex Bligh
2013-06-29 18:02 ` [Qemu-devel] [PATCH] " Alex Bligh
2013-07-01 10:23   ` Kevin Wolf [this message]
2013-07-01 11:15     ` Alex Bligh

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