From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: mingo@kernel.org, eranian@google.com,
linux-kernel@vger.kernel.org,
Markus Metzger <markus.t.metzger@intel.com>,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH] perf, nmi: fix unknown NMI warning
Date: Sat, 15 Feb 2014 10:58:43 +0100 [thread overview]
Message-ID: <20140215095843.GJ14089@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <1392425048-5309-1-git-send-email-andi@firstfloor.org>
On Fri, Feb 14, 2014 at 04:44:08PM -0800, Andi Kleen wrote:
>
> Make intel_pmu_handle_irq() take the full exit path when returning early.
This reminds me of the late-ack stuff;
The way I understand interrupts to work is that when you raise the
interrupt it gets latched, when you ACK you drop the latch. Then when it
gets re-raised while its still in progress, it gets latched again and
the irq-enable at the end of the running handler will get it to trigger
again.
So by late-ACK-ing the PMI we can miss PMIs that happen between enabling
the PMU and ACKing the PMI.
We should either re-check the overflow mask after the ACK or do the ACK
while the PMU is disabled.
next prev parent reply other threads:[~2014-02-15 9:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-15 0:44 Andi Kleen
2014-02-15 9:58 ` Peter Zijlstra [this message]
2014-02-16 18:38 ` Andi Kleen
2014-02-16 19:23 ` Peter Zijlstra
2014-02-16 19:43 ` Andi Kleen
2014-02-21 21:14 ` [tip:perf/urgent] perf, nmi: Fix " tip-bot for Markus Metzger
-- strict thread matches above, loose matches on Subject: below --
2014-02-11 23:51 [PATCH] perf, nmi: fix " Andi Kleen
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