From: Robert Love <rml@tech9.net>
To: Frank Cusack <fcusack@fcusack.com>
Cc: Ingo Oeser <ioe-lkml@rameria.de>, linux-kernel@vger.kernel.org
Subject: Re: preemption when running in the kernel
Date: Sun, 09 Nov 2003 12:56:40 -0500 [thread overview]
Message-ID: <1068400600.27320.1273.camel@localhost> (raw)
In-Reply-To: <20031109020424.A801@google.com>
On Sun, 2003-11-09 at 05:04, Frank Cusack wrote:
> Thank you for the clarification.
No problem.
> That leads me to 2 followup questions.
>
> If a task in the kernel is preempted, is a membar issued? (I believe
> so -- running another task means that the scheduler must have run,
> which will grab and release various locks thus giving us the membars.)
Yes, a memory barrier is definitely issued.
> When the preempted task resumes, is it guaranteed to run on the same CPU?
> (I wouldn't expect so, unless the task was specifically told to do that
> via hard affinity. But maybe a task preempted in the kernel is different
> then a task preempted in userland.)
No. A preempted task can reschedule on any processor.
Robert Love
prev parent reply other threads:[~2003-11-09 17:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-07 12:04 preemption when running in the kernel Frank Cusack
2003-11-08 13:01 ` Ingo Oeser
2003-11-09 0:23 ` Robert Love
2003-11-09 10:04 ` Frank Cusack
2003-11-09 17:56 ` Robert Love [this message]
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