linux-kernel - Re: [tip:perfcounters/core] perf stat: handle Ctrl-C

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Date:	Thu, 28 May 2009 21:09:59 +1000
From:	Paul Mackerras <paulus@...ba.org>
To:	mingo@...hat.com, hpa@...or.com, acme@...hat.com,
	linux-kernel@...r.kernel.org, a.p.zijlstra@...llo.nl,
	tglx@...utronix.de, cjashfor@...ux.vnet.ibm.com, mingo@...e.hu
Cc:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perfcounters/core] perf stat: handle Ctrl-C

tip-bot for Ingo Molnar writes:

> perf stat: handle Ctrl-C
> 
> Before this change, if a long-running perf stat workload was Ctrl-C-ed,
> the utility exited without displaying statistics.
> 
> After the change, the Ctrl-C gets propagated into the workload (and
> causes its early exit there), but perf stat itself will still continue
> to run and will display counter results.
> 
> This is useful to run open-ended workloads, let them run for
> a while, then Ctrl-C them to get the stats.

Unfortunately it means that if you do e.g.

$ while true; do perf stat something; done

it's impossible to kill the loop with ctrl-C.  To fix this we need to
make perf stat kill itself with the signal after printing the results,
so bash sees the died-due-to-signal exit status and stops the loop.

Paul.
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