From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
aliguori@us.ibm.com, Frediano Ziglio <freddy77@gmail.com>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2] block: avoid SIGUSR2
Date: Thu, 27 Oct 2011 14:57:31 +0100 [thread overview]
Message-ID: <20111027135731.GA21052@stefanha-thinkpad.localdomain> (raw)
In-Reply-To: <4EA95BFF.6070807@redhat.com>
On Thu, Oct 27, 2011 at 03:26:23PM +0200, Kevin Wolf wrote:
> Am 19.09.2011 16:37, schrieb Frediano Ziglio:
> > Now that iothread is always compiled sending a signal seems only an
> > additional step. This patch also avoid writing to two pipe (one from signal
> > and one in qemu_service_io).
> >
> > Work with kvm enabled or disabled. strace output is more readable (less syscalls).
> >
> > Signed-off-by: Frediano Ziglio <freddy77@gmail.com>
>
> Something in this change has bad effects, in the sense that it seems to
> break bdrv_read_em.
How does it break bdrv_read_em? Are you seeing QEMU hung with 100% CPU
utilization or deadlocked?
One interesting thing is that qemu_aio_wait() does not release the QEMU
mutex, so we cannot write to a pipe with the mutex held and then spin
waiting for the iothread to do work for us.
Exactly how kill and qemu_notify_event() were different I'm not sure
right now but it could be a factor.
Stefan
next prev parent reply other threads:[~2011-10-27 13:57 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
2011-09-19 15:15 ` Kevin Wolf
2011-10-27 13:26 ` Kevin Wolf
2011-10-27 13:57 ` Stefan Hajnoczi [this message]
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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