From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Michael Wang <wangyun@linux.vnet.ibm.com>
Cc: Xiaotian Feng <xtfeng@gmail.com>, ingo Molnar <mingo@elte.hu>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] sched: Accelerate "pick_next_entity" under special condition
Date: Wed, 25 Jan 2012 16:55:34 +0100 [thread overview]
Message-ID: <1327506934.2614.87.camel@laptop> (raw)
In-Reply-To: <4F14E54E.80904@linux.vnet.ibm.com>
On Tue, 2012-01-17 at 11:04 +0800, Michael Wang wrote:
>
> > Then what if condition 1 is true now?
>
> We can see in original code, even condition 1 is true, we
> still will use value3 if condition3 is true, like this:
>
> original:
>
> condition1 condition3 result
> true true value3
> true false value1
>
> That means if condition3 is true, we don't care whether
> condition1 is true or not because we will finally use value3.
Right, so from the original 8 possible states we used to evaluate 3*8 =
24 conditionals. The new code will reduce this to 1*4 + 2*2 + 2*3 = 14.
Now I guess the question is if it matters for the modal or average
state.
I've applied the patch since it can't be worse, but I've no idea if it
matters or not in practice.
next prev parent reply other threads:[~2012-01-25 15:55 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-16 9:37 [PATCH] sched: Accelerate "pick_next_entity" under special condition Michael Wang
2012-01-16 9:50 ` Michael Wang
2012-01-16 9:51 ` Peter Zijlstra
2012-01-16 10:34 ` Michael Wang
2012-01-17 2:36 ` [PATCH v2] " Michael Wang
2012-01-17 2:41 ` Michael Wang
2012-01-17 2:58 ` Xiaotian Feng
2012-01-17 3:04 ` Michael Wang
2012-01-25 15:55 ` Peter Zijlstra [this message]
2012-01-26 10:04 ` Ingo Molnar
2012-01-27 1:22 ` Michael Wang
2012-01-27 4:42 ` Cong Wang
2012-01-29 6:32 ` Michael Wang
2012-01-29 16:33 ` Ingo Molnar
2012-01-30 3:18 ` Michael Wang
2012-01-30 3:25 ` Cong Wang
2012-01-30 5:47 ` Michael Wang
2012-07-03 6:34 ` [PATCH] sched: remove useless code in yield_to Michael Wang
2012-07-12 5:45 ` Michael Wang
2012-07-12 14:07 ` Peter Zijlstra
2012-07-12 18:44 ` Mike Galbraith
2012-07-16 2:39 ` Michael Wang
2012-08-17 6:56 ` Michael Wang
2012-08-17 9:43 ` Peter Zijlstra
2012-08-10 3:05 ` Michael Wang
2012-08-10 3:10 ` Michael Wang
2012-08-10 5:52 ` Mike Galbraith
2012-09-04 18:50 ` [tip:sched/core] sched: Remove useless code in yield_to() tip-bot for Michael Wang
2012-01-27 0:56 ` [PATCH v2] sched: Accelerate "pick_next_entity" under special condition Michael Wang
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