From: Ingo Molnar <mingo@kernel.org>
To: Yury Norov <ynorov@caviumnetworks.com>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Akinobu Mita <mita@miraclelinux.com>,
Mike Galbraith <efault@gmx.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH] sched: remove sched_find_first_bit()
Date: Tue, 16 May 2017 10:30:42 +0200 [thread overview]
Message-ID: <20170516083042.ybenukaiiwevgqph@gmail.com> (raw)
In-Reply-To: <20170515154728.amzw3d67tw722wmu@yury-N73SV>
* Yury Norov <ynorov@caviumnetworks.com> wrote:
> I collected about 700 results in dmesg, and took 600 fastest.
> For the vanilla kernel, the average value is 368, and for patched
> kernel it is 388. It's 5% slower. But the standard deviation is
> really big for both series' - 131 and 106 cycles respectively, which
> is ~ 30%. And so, my conclusion is: there's no benefit in using
> sched_find_first_bit() comparing to find_first_bit().
Erm, so you in essence claim:
"according to measurements the new code is 5% slower, with a high, 30%
stddev, hence the new code is better!"
Basic logic fail...
Thanks,
Ingo
next prev parent reply other threads:[~2017-05-16 8:30 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-13 1:01 [PATCH] sched: remove sched_find_first_bit() Yury Norov
2017-05-14 18:09 ` Ingo Molnar
2017-05-15 15:47 ` Yury Norov
2017-05-15 15:47 ` Yury Norov
2017-05-15 16:06 ` Arnd Bergmann
2017-05-15 16:17 ` Yury Norov
2017-05-15 20:31 ` Arnd Bergmann
2017-05-15 20:31 ` Arnd Bergmann
2017-05-15 20:58 ` Yury Norov
2017-05-15 20:58 ` Yury Norov
2017-05-15 21:04 ` Arnd Bergmann
2017-05-16 8:30 ` Ingo Molnar [this message]
2017-05-17 12:16 ` Yury Norov
2017-05-18 7:14 ` Ingo Molnar
2017-05-15 14:18 ` Arnd Bergmann
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