From: Ingo Molnar <mingo@elte.hu>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Don Zickus <dzickus@redhat.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
aris@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: introduce NMI_AUTO as nmi_watchdog option
Date: Wed, 13 Jan 2010 17:35:51 +0100 [thread overview]
Message-ID: <20100113163551.GA10643@elte.hu> (raw)
In-Reply-To: <1263388422.4244.214.camel@laptop>
* Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, 2010-01-13 at 10:32 +0100, Ingo Molnar wrote:
> > other architectures have NMI concepts as well, such as Sparc64.
>
> I think both sparc64 and ppc64 fake NMIs by playing games with hw IRQ
> priorities and partial masks. But yes.
>
> One interesting 'feature' for the perf-nmi interaction is creating an idle
> scheduling class for counters, because as long as there is a counter present
> you can use his NMIs to drive the watchdog, but as soon as there are non
> left, you need to install one.
Yeah. I'd suggest to not complicate things with that initially - but to simply
create a standalone event for it and 'waste' a counter on NMI generation.
Later on it can indeed be a good feature to make the NMI watchdog 'seemless'
in the sense of it not causing any wasted hw resources - it can piggyback on
any existing NMI event. (as long as that event is at least ~1 HZ strong or so)
Ingo
next prev parent reply other threads:[~2010-01-13 16:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-11 19:16 introduce NMI_AUTO as nmi_watchdog option Don Zickus
2010-01-11 20:27 ` Cyrill Gorcunov
2010-01-11 20:33 ` Don Zickus
2010-01-11 20:51 ` Cyrill Gorcunov
2010-01-13 9:32 ` Ingo Molnar
2010-01-13 13:13 ` Peter Zijlstra
2010-01-13 16:25 ` Don Zickus
2010-01-13 16:42 ` Peter Zijlstra
2010-01-13 16:35 ` Ingo Molnar [this message]
2010-01-13 16:23 ` Don Zickus
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