From: Andi Kleen <ak@muc.de>
To: John Levon <levon@movementarian.org>
Cc: Andi Kleen <ak@muc.de>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [4/7] oprofile - NMI hook
Date: Wed, 16 Oct 2002 01:18:22 +0200 [thread overview]
Message-ID: <20021015231822.GA32749@averell> (raw)
In-Reply-To: <20021015230106.GA43030@compsoc.man.ac.uk>
On Wed, Oct 16, 2002 at 01:01:06AM +0200, John Levon wrote:
> On Wed, Oct 16, 2002 at 12:56:28AM +0200, Andi Kleen wrote:
>
> > > This patch provides a simple api to let oprofile hook into
> > > the NMI interrupt for the perfctr profiler.
> >
> > I would suggest using a notifier list instead (include/linux/notifier.h)
> > This would handle multiple users cleanly.
>
> How ? The only safe way I can see would be to spin lock around the NMI
> (and try lock when an NMI arrives). This would either make every NMI
> contend on a single spinlock, or require a NR_CPUS-sized array of
> spinlocks, which is just ugly. And that wouldn't solve the
> power-management problem - any NMI users need to collaborate to disable
> NMI generation on a suspend.
The locking issues could be fixed with read-copy-update, but you're
right that it's not a good solution right now. I take the objection
back then.
-Andi
next prev parent reply other threads:[~2002-10-15 23:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-15 22:33 [PATCH] [4/7] oprofile - NMI hook John Levon
2002-10-15 22:56 ` Andi Kleen
2002-10-15 23:01 ` John Levon
2002-10-15 23:18 ` Andi Kleen [this message]
2002-10-16 14:06 ` Keith Owens
2002-10-16 16:36 ` John Levon
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