linux-kernel - Re: [PATCH 2/2] irq: only update affinity in chip set

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Message-ID: <20090408125415.GJ18581@elte.hu>
Date:	Wed, 8 Apr 2009 14:54:15 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH 2/2] irq: only update affinity in chip set_affinity()


* Yinghai Lu <yinghai@...nel.org> wrote:

> Impact: keep affinity consistent
> 
> irq_set_affinity() and move_masked_irq() try to assign affinity 
> before calling chip set_affinity(). some archs are assigning again 
> in set_affinity again.
> 
> something like:
> cpumask_cpy(desc->affinity, mask);
> desc->chip->set_affinity(mask);
> 
> in the failing path, affinity should not be touched.
> 
> also set_extra_move_desc() ( called by set_affinity) will rely on 
> the old affinity to decide if need to move irq_desc to different 
> node when logical flat apic mode is used.
> 
> So try remove those assignment, and make some missed arch to 
> assign affinity in their set_affinity.
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> 
> --
>  arch/alpha/kernel/sys_dp264.c         |    6 ++++--
>  arch/alpha/kernel/sys_titan.c         |    3 ++-
>  arch/arm/common/gic.c                 |    1 +
>  arch/cris/arch-v32/kernel/irq.c       |    1 +
>  arch/ia64/kernel/iosapic.c            |    3 +++
>  arch/ia64/sn/kernel/irq.c             |    3 +++
>  arch/mips/cavium-octeon/octeon-irq.c  |    6 ++++++
>  arch/mips/sibyte/bcm1480/irq.c        |    2 ++
>  arch/mips/sibyte/sb1250/irq.c         |    2 ++
>  arch/powerpc/platforms/pseries/xics.c |    5 +++++
>  arch/powerpc/sysdev/mpic.c            |    2 ++
>  arch/sparc/kernel/irq_64.c            |    7 +++++++
>  drivers/xen/events.c                  |    2 ++
>  kernel/irq/manage.c                   |    6 ++----
>  kernel/irq/migration.c                |    8 +++-----
>  15 files changed, 45 insertions(+), 12 deletions(-)

Hm, this spreads a lot of instances of identical lines:

   cpumask_copy(irq_desc[irq].affinity, mask_val);

all around architectures. How is that an improvement?

	Ingo
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