linux-kernel - Re: Epic regression in throughput since v2.6.23

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Message-ID: <20090913154744.GA27066@elte.hu>
Date:	Sun, 13 Sep 2009 17:47:44 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Serge Belyshev <belyshev@...ni.sinp.msu.ru>
Cc:	Con Kolivas <kernel@...ivas.org>, linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mike Galbraith <efault@....de>
Subject: Re: Epic regression in throughput since v2.6.23


* Serge Belyshev <belyshev@...ni.sinp.msu.ru> wrote:

> Note that the disabling NEW_FAIR_SLEEPERS doesn't fix 3% 
> regression from v2.6.23, but instead makes "make -j4" runtime 
> another 2% worse (27.05 -> 27.72).

ok - thanks for the numbers, will have a look.

> ---
>  tools/perf/builtin-stat.c |   18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)

> +	// quick ugly hack: if a "--" appears in the command, treat is as
> +	// a delimiter and use remaining part as a "cleanup command",
> +	// not affecting performance counters.
> +	cleanup = cleanup_argc = 0;
> +	for (j = 1; j < (argc-1); j ++) {
> +		if (!strcmp (argv[j], "--")) {
> +			cleanup = j + 1;
> +			cleanup_argc = argc - j - 1;
> +			argv[j] = NULL;
> +			argc = j;
> +		}
> +	}

Nice feature!

How about doing it a bit cleaner, as '--repeat-prepare' and 
'--repeat-cleanup' options, to allow both pre-repeat and post-repeat 
cleanup ops to be done outside of the measured period?

	Ingo
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