From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Cc: pbonzini@redhat.com, xen-devel@lists.xensource.com,
avi@redhat.com,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Subject: Re: [Qemu-devel] [PATCH v3 6/6] qemu_calculate_timeout: increase minimum timeout to 1h
Date: Fri, 10 Feb 2012 00:26:40 +0000 [thread overview]
Message-ID: <201202100026.40727.paul@codesourcery.com> (raw)
In-Reply-To: <1327688498-12362-6-git-send-email-stefano.stabellini@eu.citrix.com>
> There is no reason why the minimum timeout should be 1sec, it could
> easily be 1h and we would save lots of cpu cycles.
No.
The reason we have this is because there are bits of code that rely on
polling. IIRC slirp and the floppy DMA engine were the main culprits.
qemu_calculate_timeout is an ugly hack to poll at least once a second,
allowing the guest to make forward progress when we miss an event.
If you think you've fixed all those polling places then you should remove the
timeout altogether and block indefinitely. A 1h timeout is almost certainly
not the right answer.
Paul
next prev parent reply other threads:[~2012-02-10 0:26 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-27 18:20 [Qemu-devel] [PATCH v3 0/6] prevent Qemu from waking up needlessly Stefano Stabellini
2012-01-27 18:21 ` [Qemu-devel] [PATCH v3 1/6] xen: do not initialize the interval timer emulator Stefano Stabellini
2012-01-27 19:09 ` Jan Kiszka
2012-01-30 11:39 ` Stefano Stabellini
2012-01-30 15:13 ` Jan Kiszka
2012-01-27 18:21 ` [Qemu-devel] [PATCH v3 2/6] xen: disable rtc_clock Stefano Stabellini
2012-01-27 20:08 ` Paolo Bonzini
2012-01-30 11:58 ` Stefano Stabellini
2012-01-27 18:21 ` [Qemu-devel] [PATCH v3 3/6] xen: introduce an event channel for buffered io event notifications Stefano Stabellini
2012-01-27 18:21 ` [Qemu-devel] [PATCH v3 4/6] timers: the rearm function should be able to handle delta = INT64_MAX Stefano Stabellini
2012-01-27 18:21 ` [Qemu-devel] [PATCH v3 5/6] qemu_next_alarm_deadline: check the expire time of a clock only if it is enabled Stefano Stabellini
2012-01-27 18:21 ` [Qemu-devel] [PATCH v3 6/6] qemu_calculate_timeout: increase minimum timeout to 1h Stefano Stabellini
2012-02-10 0:26 ` Paul Brook [this message]
2012-02-10 8:03 ` Paolo Bonzini
2012-02-10 9:52 ` Paul Brook
2012-02-10 10:45 ` Paolo Bonzini
2012-02-10 11:09 ` Paul Brook
2012-02-10 11:19 ` Stefano Stabellini
2012-02-10 11:18 ` Paolo Bonzini
2012-02-10 11:32 ` Jan Kiszka
2012-02-10 17:07 ` Stefano Stabellini
2012-02-10 23:34 ` Paul Brook
2012-02-13 11:52 ` Stefano Stabellini
2012-02-14 10:52 ` Paul Brook
2012-02-14 11:55 ` Stefano Stabellini
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