From: Paolo Bonzini <pbonzini@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: aliguori@us.ibm.com, Frediano Ziglio <freddy77@gmail.com>,
Qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2] block: avoid SIGUSR2
Date: Mon, 19 Sep 2011 17:25:38 +0200 [thread overview]
Message-ID: <4E775EF2.6090504@redhat.com> (raw)
In-Reply-To: <4E775BBA.3040904@redhat.com>
On 09/19/2011 05:11 PM, Kevin Wolf wrote:
>> > I think it is possible to go a step further, turn
>> > posix_aio_process_queue into a bottom half and get rid of the pipe
>> > altogether. This in turn would remove the only real user of
>> > io_process_queue in qemu_aio_set_fd_handler. However, this is already a
>> > nice improvement.
> But without the fd, wouldn't the I/O thread possibly wait for much
> longer until its select() times out and it starts processing BHs?
Hmm, in qemu_aio_wait yes... In the normal qemu event loop, however,
bottom halves exit the select loop with qemu_notify_event(). qemu
currently has a 1-second timeout for the select, but it should work just
as well with an infinite timeout. If it doesn't, it's a bug.
It should be possible to turn posix_aio_process_queue into a bottom
half, but the pipe is still necessary in order to exit the qemu_aio_wait
select loop and schedule the bottom half.
Paolo
next prev parent reply other threads:[~2011-09-19 15:25 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-19 14:37 [Qemu-devel] [PATCH v2] block: avoid SIGUSR2 Frediano Ziglio
2011-09-19 15:02 ` Paolo Bonzini
2011-09-19 15:11 ` Kevin Wolf
2011-09-19 15:25 ` Paolo Bonzini [this message]
2011-09-19 15:15 ` Kevin Wolf
2011-10-27 13:26 ` Kevin Wolf
2011-10-27 13:57 ` Stefan Hajnoczi
2011-10-27 14:15 ` Kevin Wolf
2011-10-27 14:32 ` Kevin Wolf
2011-10-28 11:33 ` Kevin Wolf
2011-10-28 11:35 ` Kevin Wolf
2011-10-28 11:50 ` Paolo Bonzini
2011-10-28 12:29 ` Kevin Wolf
2011-10-28 12:31 ` Stefan Hajnoczi
2011-10-28 15:58 ` Paolo Bonzini
2011-10-31 2:10 ` Zhi Yong Wu
2011-10-28 12:20 ` Cleber Rosa
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