From: Peter Zijlstra <peterz@infradead.org>
To: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: linux-kernel@vger.kernel.org,
"Stanislaw Gruszka" <sgruszka@redhat.com>,
"Ingo Molnar" <mingo@elte.hu>,
"Spencer Candland" <spencer@bluehost.com>,
"Oleg Nesterov" <oleg@redhat.com>,
"Balbir Singh" <balbir@in.ibm.com>,
"Américo Wang" <xiyou.wangcong@gmail.com>
Subject: Re: [PATCH -tip 1/3] introduce task_times() to replace task_{u,s}time() pair
Date: Thu, 26 Nov 2009 11:25:44 +0100 [thread overview]
Message-ID: <1259231144.4273.27.camel@twins> (raw)
In-Reply-To: <4B0E16AE.906@jp.fujitsu.com>
On Thu, 2009-11-26 at 14:48 +0900, Hidetoshi Seto wrote:
> Functions task_{u,s}time() are called in pair in almost all
> cases. However task_stime() is implemented to call task_utime()
> from its inside, so such paired calls run task_utime() twice.
>
> It means we do heavy divisions (div_u64 + do_div) twice to get
> utime and stime which can be obtained at same time by one set
> of divisions.
>
> This patch introduces a function task_times(*tsk, *utime, *stime)
> to retrieve utime and stime at once in better, optimized way.
>
> Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
OK, the patch looks good, but it does not solve those non monotonic
times funnies that started all this, right?
next prev parent reply other threads:[~2009-11-26 10:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-20 4:44 [PATCH tip/sched/core] introduce task_times() to replace task_[us]time() pair Hidetoshi Seto
2009-11-23 10:28 ` Stanislaw Gruszka
2009-11-24 5:38 ` Hidetoshi Seto
2009-11-24 7:08 ` Hidetoshi Seto
2009-11-26 5:48 ` [PATCH -tip 1/3] introduce task_times() to replace task_{u,s}time() pair Hidetoshi Seto
2009-11-26 10:25 ` Peter Zijlstra [this message]
2009-11-27 0:37 ` Hidetoshi Seto
2009-11-26 12:33 ` [tip:sched/core] sched: Introduce " tip-bot for Hidetoshi Seto
2009-11-26 5:49 ` [PATCH -tip 2/3] remove task_{u,s,g}time() Hidetoshi Seto
2009-11-26 10:26 ` Peter Zijlstra
2009-11-26 12:33 ` [tip:sched/core] sched: Remove task_{u,s,g}time() tip-bot for Hidetoshi Seto
2009-11-26 5:49 ` [PATCH -tip 3/3] define nsecs_to_jiffies() Hidetoshi Seto
2009-11-26 10:27 ` Peter Zijlstra
2009-11-26 12:34 ` [tip:sched/core] sched, time: Define nsecs_to_jiffies() tip-bot for Hidetoshi Seto
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