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RE: [Xen-devel] cpuidle causing Dom0 soft lockups

To: "Ke Yu" <ke.yu@xxxxxxxxx>,"Kevin Tian" <kevin.tian@xxxxxxxxx>
Subject: RE: [Xen-devel] cpuidle causing Dom0 soft lockups
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Fri, 05 Feb 2010 14:59:29 +0000
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>>> "Tian, Kevin" <kevin.tian@xxxxxxxxx> 05.02.10 12:16 >>>
>Possible options is to take jiffies, system timestamp, and per-cpu
>timestamp in stop_hz_timer, to generate a local latest value. Or
>a per-cpu jiffies can be generated in per-cpu timer interrupt, which
>is only used in per-cpu style like in stop_hz_timer.

That was my next thought too - but it doesn't work (unless I made a
blatant mistake). Not only does it not get the interrupt rate down,
it even grows it on the duty CPU, and it creates visible brief hangs
as well a rushes of time.

Next I'll do is try to detect when the duty CPU is de-scheduled, and
move on the duty to one that is scheduled (i.e. one that is currently
executing timer_interrupt()).

Jan


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