[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread" |
Date: |
Thu, 08 Oct 2009 16:51:02 -0500 |
User-agent: |
Thunderbird 2.0.0.23 (X11/20090825) |
Michael S. Tsirkin wrote:
BTW, tried looking at the code.
I saw some (unrelated) issues:
static void aio_signal_handler(int signum)
{
if (posix_aio_state) {
char byte = 0;
write(posix_aio_state->wfd, &byte, sizeof(byte));
}
qemu_service_io();
}
And qemu_service_io does a *ton* of things.
It just does a cpu_exit().
Questions:
- Do we need the call to qemu_service_io? Seems to
behave the same with and without it.
Where you run into trouble is when you have a guest that has no periodic
timer and needs a mechanism to break out of the tcg loop whenever an IO
operation completes. See
Author: aliguori <address@hidden>
Date: Wed Oct 8 19:50:24 2008 +0000
Fix IO performance regression in sparc
- Are all of the data structures touched by qemu_service_io
protected by blocking signals before access?
cpu_exit is pretty careful to not do anything that could be racey.
Also:
- let's use signalfd on linux, if available?
signalfd doesn't help. In fact, we originally used signalfd and it
caused a regression.
- for SIGALARM, maybe timerfd?
Or just get rid of SIGALARM...
Regards,
Anthony Liguori
- [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", (continued)
- [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", Michael S. Tsirkin, 2009/10/07
- [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", malc, 2009/10/07
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", Jamie Lokier, 2009/10/07
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", malc, 2009/10/07
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", Jamie Lokier, 2009/10/08
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", malc, 2009/10/08
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", Jamie Lokier, 2009/10/09
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", malc, 2009/10/09
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", Michael S. Tsirkin, 2009/10/08
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", Anthony Liguori, 2009/10/08
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread",
Anthony Liguori <=
- Re: [Qemu-devel] Re: [PATCH] Revert "posix-aio-compat: avoid signal race when spawning a thread", Jamie Lokier, 2009/10/09