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Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signal
From: |
Ian Jackson |
Subject: |
Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals. |
Date: |
Tue, 26 Aug 2008 14:38:52 +0100 |
Anthony Liguori writes ("[Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle
terminating signals."):
> The race I know of is that you may get an aio signal completion before
> select but after you've already qemu_aio_poll()'d. In practice, we only
> sleep for 10ms at a time in select() so the race is handled by that. If
> we wanted to increase the amount of time we slept, we would have to
> handle this race.
Yes. And, 10ms is too long anyway for reasonable performance. During
my merge with upstream I found that the qemu aio functionality (which
was done quite differently to the old xen ioemu) caused a severe
performance regression under some conditions because of this race.
> In KVM, we sleep for 1s in select() and use signalfd() to receive the
> aio notifications. For older hosts, we emulate signalfd using a thread
> and the pipe-to-self trick.
Why does it need a thread ? You can just write to the pipe in the
signal handler. I'll post my code.
Ian.
- Re: [Qemu-devel] [PATCH 02/13] add DisplayState->idle, (continued)
- [Qemu-devel] [PATCH 07/13] xen: add console backend driver., Gerd Hoffmann, 2008/08/21
- [Qemu-devel] [PATCH 01/13] Handle terminating signals., Gerd Hoffmann, 2008/08/21
- Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Anthony Liguori, 2008/08/21
- Message not available
- Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Ian Jackson, 2008/08/26
- Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Gerd Hoffmann, 2008/08/26
- Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Ian Jackson, 2008/08/26
- Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Gerd Hoffmann, 2008/08/26
- Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Jamie Lokier, 2008/08/26
- Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Anthony Liguori, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals.,
Ian Jackson <=
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Avi Kivity, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Jamie Lokier, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Anthony Liguori, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Ian Jackson, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Anthony Liguori, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Ian Jackson, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Samuel Thibault, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Anthony Liguori, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Jamie Lokier, 2008/08/26
- Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals., Jamie Lokier, 2008/08/26