linux-kernel - Re: [patch] speed up / fix the new generic semaphore code (fix AIM7 40% regression with 2.6.26-rc1)

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Message-ID: <871w4bnan9.fsf@basil.nowhere.org>
Date:	Fri, 09 May 2008 10:29:14 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>, Ingo Molnar <mingo@...e.hu>,
	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
	Matthew Wilcox <matthew@....cx>,
	LKML <linux-kernel@...r.kernel.org>,
	Alexander Viro <viro@....linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [patch] speed up / fix the new generic semaphore code (fix AIM7 40% regression with 2.6.26-rc1)

Linus Torvalds <torvalds@...ux-foundation.org> writes:
>
> Well, it turns out that Ingo's fixed statistics actually put the real cost 
> in fcntl/ioctl/open/release:
>
>     310  down <= lock_kernel <= sys_fcntl <= system_call_after_swapgs <

That must be ->fasync? If it was file locks the lock_kernel would not
be inlined into sys_fcntl. Or is that an truncated back trace?

-Andi (wondering if he should plug ->fasync_unlocked again ...)
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