From: lists@frednet.dyndns.org
Date: Mon, 5 Feb 2001 15:19:17 -0600
To: Rusty Russell <rusty@linuxcare.com.au>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Hot swap CPU support for 2.4.1@
Message-ID: <20010205151917.A17110@frednet.dyndns.org>
In-Reply-To: <E14PcpU-0004U1-00@halfway>
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In-Reply-To: <E14PcpU-0004U1-00@halfway>; from rusty@linuxcare.com.au on Mon, Feb 05, 2001 at 03:00:40PM +1100
Sender: linux-kernel-owner@vger.kernel.org


Would any special hardware besides a multi-cpu system be necessarey to
test this out?


Matthew Fredrickson

On Mon, Feb 05, 2001 at 03:00:40PM +1100, Rusty Russell wrote:
> Hi all,
> 
> I did the infrastructure, Anton did the bugfinding and PPC support,
> aka. the hard stuff.  Other architectures need to implement
> __cpu_disable, __cpu_die and __cpu_up for them to work.  Volunteers
> appreciated.
> 
> 	This patch allows you to down & up CPUs as follows:
> 	# echo 0 > /proc/sys/cpu/0/online
> 	# echo 1 > /proc/sys/cpu/0/online
> 
> The relatively trivial patch works as follows:
> 
> 1) Implements synchronize_kernel() (thanks Andi Kleen for forwarding
>    Paul McKenney's quiescent-state ideas) which waits for a schedule
>    on all CPUs.
> 2) All CPU numbers are now physical: removes cpu_number_map,
>    cpu_logical_map and smp_num_cpus.
> 3) Adds cpu_online(cpu) and cpu_num_online() macros.
> 4) Adds cpu_down() and cpu_up() calls, which call arch-specific
>    __cpu_disable(cpu), __cpu_die(cpu) and __cpu_up(cpu).
> 5) Fixes schedule() to check allowed_cpus even if rescheduling same
>    task.
> 
> Since it's 60k long, mime attached bzip2.
> 
> Go hack!
> Rusty Russell & Anton Blanchard
> --


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