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Date:   Fri, 23 Aug 2019 10:07:06 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Josh Hunt <johunt@akamai.com>
Cc:     linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        acme@kernel.org, alexander.shishkin@linux.intel.com,
        jolsa@redhat.com, namhyung@kernel.org, bpuranda@akamai.com
Subject: Re: [PATCH] perf/x86/intel: restrict period on Nehalem
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On Mon, Aug 19, 2019 at 07:13:31PM -0400, Josh Hunt wrote:
> We see our Nehalem machines reporting 'perfevents: irq loop stuck!' in
> some cases when using perf:
> 
> perfevents: irq loop stuck!

> I found that a period limit of 32 was the lowest I could set it to without
> the problem reoccurring. The idea for the patch and approach to find the
> target value were suggested by Ingo and Thomas.
> 
> Signed-off-by: Josh Hunt <johunt@akamai.com>
> Reported-by: Bhupesh Purandare <bpuranda@akamai.com>
> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
> Suggested-by: Ingo Molnar <mingo@redhat.com>
> Link: https://lore.kernel.org/lkml/20150501070226.GB18957@gmail.com/
> Link: https://lore.kernel.org/lkml/alpine.DEB.2.21.1908122133310.7324@nanos.tec.linutronix.de/

Thanks!