From: Robert Love <rml@tech9.net>
To: Ingo Oeser <ioe-lkml@rameria.de>
Cc: Frank Cusack <fcusack@fcusack.com>, linux-kernel@vger.kernel.org
Subject: Re: preemption when running in the kernel
Date: Sat, 08 Nov 2003 19:23:05 -0500 [thread overview]
Message-ID: <1068337385.27320.203.camel@localhost> (raw)
In-Reply-To: <200311081402.07345.ioe-lkml@rameria.de>
On Sat, 2003-11-08 at 08:01, Ingo Oeser wrote:
> While having preemption disabled or while actually holding a spinlock,
> preemption is disabled.
>
> Disabling preemption is modifying a count, which must reach 0 again to
> have preemption enabled and trigger an reschedule, if needed.
>
> Think of it roughly as a "counter of reasons to not preempt". If there
> are no reasons anymore, then we preempt.
Hi, Ingo.
This is an accurate description of 2.6, but Frank said for 2.4.
So, Frank, this is correct for 2.6 or 2.4 with the preempt-kernel patch,
but not a stock 2.4 kernel. A stock 2.4 kernel will never preempt a
task running inside the kernel.
Robert Love
next prev parent reply other threads:[~2003-11-09 0:23 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 [this message]
2003-11-09 10:04 ` Frank Cusack
2003-11-09 17:56 ` Robert Love
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