Subject: Re: [PATCH -tip 1/3] introduce task_times() to replace
 task_{u,s}time() pair
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>,
       =?ISO-8859-1?Q?Am=E9rico?= Wang <xiyou.wangcong@gmail.com>
In-Reply-To: <4B0E16AE.906@jp.fujitsu.com>
References: <4B061E9A.8040100@jp.fujitsu.com>
	 <20091123102806.GD25978@dhcp-lab-161.englab.brq.redhat.com>
	 <4B0B714C.9080607@jp.fujitsu.com> <4B0B8683.6020104@jp.fujitsu.com>
	 <4B0E16AE.906@jp.fujitsu.com>
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Date: Thu, 26 Nov 2009 11:25:44 +0100
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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?

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