From: Russell King <rmk@arm.linux.org.uk>
To: Robert Love <rml@tech9.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2.5: preemptive kernel on UP
Date: Tue, 5 Mar 2002 00:43:25 +0000 [thread overview]
Message-ID: <20020305004325.C32309@flint.arm.linux.org.uk> (raw)
In-Reply-To: <1015287099.865.3.camel@phantasy>
In-Reply-To: <1015287099.865.3.camel@phantasy>; from rml@tech9.net on Mon, Mar 04, 2002 at 07:11:23PM -0500
On Mon, Mar 04, 2002 at 07:11:23PM -0500, Robert Love wrote:
> During 2.5.5-pre, an optimization was made that removed schedule_tail
> from UP kernels. This causes the initial preempt_count of a new task,
> which starts at 1, to never decrement to zero and thus never become
> preemptible.
>
> Thanks to everyone who pointed out the lousy performance - it took
> awhile to find but it should be fixed now. Please comment if not.
>
> Patch is against 2.5.6-pre2 and is critical for all UP+preempt users.
>
> Robert Love
>
> diff -urN linux-2.5.6-pre2/arch/alpha/kernel/entry.S linux/arch/alpha/kernel/entry.S
> --- linux-2.5.6-pre2/arch/alpha/kernel/entry.S Fri Mar 1 17:21:14 2002
> +++ linux/arch/alpha/kernel/entry.S Mon Mar 4 17:49:27 2002
> @@ -495,7 +495,7 @@
> ret $31,($26),1
> .end alpha_switch_to
>
> -#ifdef CONFIG_SMP
> +#ifdef CONFIG_SMP || CONFIG_PREEMPT
Surely you really don't mean this?
--
Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux
http://www.arm.linux.org.uk/personal/aboutme.html
next prev parent reply other threads:[~2002-03-05 0:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-05 0:11 [PATCH] 2.5: preemptive kernel on UP Robert Love
2002-03-05 0:43 ` Russell King [this message]
2002-03-05 0:51 ` Robert Love
2002-03-05 0:53 ` Russell King
2002-03-05 0:58 ` Robert Love
2002-03-05 1:55 ` Alan Cox
2002-03-05 1:43 ` Robert Love
2002-03-05 4:40 ` Ben Clifford
2002-03-05 1:56 ` yodaiken
2002-03-06 19:17 ` george anzinger
2002-03-06 20:21 ` Robert Love
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