linux-kernel - Re: [PATCH v2] sched: Accelerate "pick_next

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4F260DAE.4000008@gmail.com>
Date:	Mon, 30 Jan 2012 11:25:34 +0800
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	Michael Wang <wangyun@...ux.vnet.ibm.com>
CC:	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Xiaotian Feng <xtfeng@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] sched: Accelerate "pick_next_entity" under special
 condition

On 01/30/2012 11:18 AM, Michael Wang wrote:
> But the sched.o under ./arch/x86/kernel/cpu/ still not change...
> I think I may checking the wrong file, because this patch is for fair.c.
>
> And the fair.o changed after apply the patch, the size is a little
> bigger, and the gcc generated code changed.
>
> But I still don't know what can we get from this result? Bigger size is
> caused by additional code, but these additional code will help to step
> over some unnecessary code under special condition, looks like some
> balance between size and performance...

As your patch reduces the conditionals from 24 to 14, so it is possible 
that it also reduces the size of the code too. This is Ingo's point.

You need to check the diff to see why gcc actually generates bigger code.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/