From: Andi Kleen <ak@linux.intel.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andi Kleen <andi@firstfloor.org>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
davidlohr.bueso@hp.com, rafael.j.wysocki@intel.com,
lenb@kernel.org
Subject: Re: [PATCH] Optimize int_sqrt for small values for faster idle
Date: Mon, 1 Feb 2016 13:36:22 -0800 [thread overview]
Message-ID: <20160201213622.GA15302@tassilo.jf.intel.com> (raw)
In-Reply-To: <87y4b4azsy.fsf@rasmusvillemoes.dk>
On Mon, Feb 01, 2016 at 10:25:17PM +0100, Rasmus Villemoes wrote:
> On Thu, Jan 28 2016, Andi Kleen <andi@firstfloor.org> wrote:
>
> > From: Andi Kleen <ak@linux.intel.com>
> >
> > The menu cpuidle governor does at least two int_sqrt() each time
> > we go into idle in get_typical_interval to compute stddev
> >
> > int_sqrts take 100-120 cycles each. Short idle latency is important
> > for many workloads.
> >
>
> If you want to optimize get_typical_interval(), why not just take the
> square root out of the equation (literally)?
>
> Something like
Looks good. Yes that's a better fix.
-Andi
next prev parent reply other threads:[~2016-02-01 21:36 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 21:42 [PATCH] Optimize int_sqrt for small values for faster idle Andi Kleen
2016-01-28 22:04 ` kbuild test robot
2016-01-28 22:11 ` kbuild test robot
2016-01-28 22:15 ` Joe Perches
2016-01-28 22:40 ` Andi Kleen
2016-01-28 22:22 ` Joe Perches
2016-01-28 22:29 ` Eric Dumazet
2016-01-28 22:30 ` Andi Kleen
2016-01-29 3:59 ` Rafael J. Wysocki
2016-01-31 7:27 ` Thomas Rohwer
2016-02-01 21:25 ` Rasmus Villemoes
2016-02-01 21:36 ` Andi Kleen [this message]
2016-02-01 23:08 ` Rasmus Villemoes
2016-02-02 0:00 ` Andi Kleen
2016-02-02 0:36 ` Eric Dumazet
2016-02-02 20:46 ` Rasmus Villemoes
2016-02-02 21:30 ` Eric Dumazet
2017-07-20 10:10 ` Peter Zijlstra
2017-07-24 13:28 ` Eric Dumazet
2016-02-07 21:32 ` Rasmus Villemoes
2016-02-09 20:44 ` Andi Kleen
2016-02-10 13:31 ` Fengguang Wu
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