From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 0/2] Make simpletrace work on Windows
Date: Fri, 09 Sep 2011 13:12:34 +0200 [thread overview]
Message-ID: <4E69F4A2.3070405@redhat.com> (raw)
In-Reply-To: <1315561022-25386-1-git-send-email-stefanha@linux.vnet.ibm.com>
On 09/09/2011 11:37 AM, Stefan Hajnoczi wrote:
> The 'simple' trace backend uses pthreads and does not work on Windows. These
> patches switch from pthreads to glib so that the code builds on all platforms
> supported by glib.
>
> Only one thing I'm unhappy about: the simpletrace write-out thread used to
> block all signals. I have removed that code and don't expect glib to do it for
> me. I'm not sure if there is a problem if signal handlers are invoked in the
> write-out thread instead of a QEMU thread. Any thoughts?
I am afraid of concurrent manipulation of the alarm timer info (in
host_alarm_handler) if SIGALRM is triggered in the write-out thread.
This would be with -clock unix. I'd just leave the pthread_sigmask code
#ifdef'ed in.
By the way, I think this is the exact problem that Windows has running
with the dynticks timer instead of the mmsystem timer. We can fix this
particular problem by transferring host_alarm_handler's work to a bottom
half, but in general I think leaving signals enabled is dangerous.
Paolo
next prev parent reply other threads:[~2011-09-09 11:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-09 9:37 [Qemu-devel] [PATCH 0/2] Make simpletrace work on Windows Stefan Hajnoczi
2011-09-09 9:37 ` [Qemu-devel] [PATCH 1/2] trace: portable simple trace backend using glib Stefan Hajnoczi
2011-09-20 10:31 ` Jan Kiszka
2011-09-20 10:52 ` Paolo Bonzini
2011-09-20 10:58 ` Jan Kiszka
2011-09-20 12:01 ` Stefan Hajnoczi
2011-09-09 9:37 ` [Qemu-devel] [PATCH 2/2] trace: use binary file open mode in simpletrace Stefan Hajnoczi
2011-09-09 11:12 ` Paolo Bonzini [this message]
2011-09-20 9:05 ` [Qemu-devel] [PATCH 0/2] Make simpletrace work on Windows hkran
2011-09-20 9:57 ` Stefan Hajnoczi
2011-09-20 10:15 ` Zhi Yong Wu
2011-09-23 5:58 ` hkran
2011-09-20 10:20 ` Avi Kivity
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