From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: bad interaction between boosted idle vcpus and
 csched's tickling?
Date: Fri, 7 May 2010 14:02:44 +0100
Message-ID: <C809CE04.13A84%keir.fraser@eu.citrix.com>
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To: Jan Beulich <JBeulich@novell.com>
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On 07/05/2010 13:36, "Jan Beulich" <JBeulich@novell.com> wrote:

> Keir,
> 
> isn't there a problem after the change to handle tasklets in idle vcpus
> in that {default,acpi_processor}_idle() will put the vcpu to sleep with
> boosted priority still in place, hence preventing it from being tickled
> and/or needlessly tickling other CPUs?

See the comment above tasklet_list definition in tasklet.c: we always run
through the scheduler when tasklets are added/removed. That is explicitly to
get the idle thread's priority set correctly.

I think this could be handled better though, and also in the current
approach I actually still probably don't have enough raise_softirq() calls.
:-) I will take another look and see if I can make things more obvious and
robust.

 Thanks,
 Keir

> Jan
>