From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Steven Noonan <steven@uplinklabs.net>
Cc: Ben Guthro <ben@guthro.net>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
Ingo Molnar <mingo@elte.hu>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: bisected: 'perf top' causing soft lockups under Xen
Date: Wed, 15 Feb 2012 10:25:44 +0100 [thread overview]
Message-ID: <1329297944.2293.36.camel@twins> (raw)
In-Reply-To: <20120215085737.GA13722@asmodeus>
On Wed, 2012-02-15 at 00:57 -0800, Steven Noonan wrote:
> It seems to me that there are two options for fixing this, but I'm
> probably lacking the necessary context (or experience with Xen). Either:
>
> - The patch provided by Ben needs to have additional work to specially
> handle IRQ_WORK_VECTOR, since it seems to be a special case where
> there's no event channel attached for it. Perhaps adding an event
> channel for this is the fix? Seems high-overhead, but I lack a good
> understanding of how interrupts are handled in Xen.
So that's a self-IPI, is Xen failing to implement this?
> or
>
> - Perf needs to be "enlightened" about Xen and avoid sending an IPI in
> the first place.
Uhm, no. If anything Xen should simply not implement
arch_irq_work_raise(). The callbacks are then ran from the timer
interrupt.
next prev parent reply other threads:[~2012-02-15 9:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-10 2:32 bisected: 'perf top' causing soft lockups under Xen Steven Noonan
2012-02-10 16:12 ` Konrad Rzeszutek Wilk
2012-02-10 17:24 ` Peter Zijlstra
2012-02-10 17:28 ` Peter Zijlstra
2012-02-10 19:04 ` Konrad Rzeszutek Wilk
2012-02-11 2:34 ` Ben Guthro
2012-02-12 20:50 ` Steven Noonan
2012-02-15 8:57 ` Steven Noonan
2012-02-15 9:25 ` Peter Zijlstra [this message]
2012-02-15 9:32 ` Steven Noonan
2012-02-15 17:14 ` Konrad Rzeszutek Wilk
2012-02-15 16:17 ` Konrad Rzeszutek Wilk
2012-03-20 15:23 ` Konrad Rzeszutek Wilk
2012-03-20 15:33 ` Peter Zijlstra
2012-02-10 19:14 ` Steven Noonan
2012-02-10 19:27 ` Steven Noonan
2012-02-10 19:29 ` Arnaldo Carvalho de Melo
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