linux-kernel - Re: [PATCH] perf: fix interrupt handler timing harness

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Message-ID: <51DACE08.5030109@intel.com>
Date:	Mon, 08 Jul 2013 07:34:48 -0700
From:	Dave Hansen <dave.hansen@...el.com>
To:	Stephane Eranian <eranian@...gle.com>
CC:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	dave.hansen@...ux.intel.com, ak@...ux.intel.com, jolsa@...hat.com
Subject: Re: [PATCH] perf: fix interrupt handler timing harness

On 07/04/2013 03:30 PM, Stephane Eranian wrote:
> There was an misunderstanding on the API of the do_div()
> macro. It returns the remainder of the division and this
> was not what the function expected leading to disabling the
> interrupt latency watchdog.

"Misunderstanding" is a very kind term for what I did there.  Stephane,
were you actually running in to the new cpu limit, or were you just
trying to update kernel.perf_event_max_sample_rate?

BTW, I also did the same thing in 2ab00456:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2ab00456ea8a0d79acb1390659b98416111880b2

I'll have a patch out shortly for that one, but its damage would be
limited to a bogus printk.
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