From: Daniel Phillips <phillips@innominate.de>
To: ludovic fernandez <ludovic.fernandez@sun.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2.4.0-prerelease: preemptive kernel.
Date: Thu, 04 Jan 2001 08:35:02 +0100 [thread overview]
Message-ID: <3A5427A6.26F25A8A@innominate.de> (raw)
In-Reply-To: <3A53D863.53203DF4@sun.com>
ludovic fernandez wrote:
> The following patch makes the kernel preemptable.
> It is against 2.4.0-prerelease on for i386 only.
> It should work for UP and SMP even though I
> didn't validate it on SMP.
> Comments are welcome.
I was expecting to see this sometime in 2.5, not quite so soon...
The key idea here is to disable preemption on spin lock and reenable on
spin unlock. That's a practical idea, highly compatible with the
current way of doing things. Its a fairly heavy hit on spinlock
performance, but maybe the overall performance hit is small. Benchmarks
are needed.
A more ambitious way to proceed is to change spinlocks so they can sleep
(not in interrupts of course). There would not be any extra overhead
for this on spin_lock (because the sleep test is handled off the fast
path) but spin_unlock gets a little slower - it has to test and jump on
a flag if there are sleepers.
--
Daniel
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next prev parent reply other threads:[~2001-01-04 7:38 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-04 1:56 [PATCH] 2.4.0-prerelease: preemptive kernel ludovic fernandez
2001-01-04 7:35 ` Daniel Phillips [this message]
2001-01-04 8:11 ` Andi Kleen
2001-01-04 12:32 ` Anton Blanchard
2001-01-04 12:44 ` Andi Kleen
2001-01-04 21:54 ` Nigel Gamble
2001-01-04 21:39 ` Nigel Gamble
2001-01-04 22:09 ` Andi Kleen
2001-01-04 22:28 ` Nigel Gamble
2001-01-04 8:43 ` ludovic fernandez
2001-01-04 22:10 ` Roger Larsson
2001-01-04 23:16 ` ludovic fernandez
2001-01-05 0:10 ` Nigel Gamble
2001-01-05 0:36 ` ludovic fernandez
2001-01-05 0:45 ` Andi Kleen
2001-01-05 1:13 ` Alan Olsen
2001-01-05 5:29 ` george anzinger
2001-01-05 6:45 ` ludovic fernandez
2001-01-05 8:10 ` george anzinger
2001-01-04 21:28 ` Nigel Gamble
2001-01-04 9:00 ` David Woodhouse
2001-01-04 16:17 ` Rik van Riel
2001-01-04 20:06 ` Nigel Gamble
2001-01-04 20:36 ` ludovic fernandez
2001-01-05 0:56 ` Daniel Phillips
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