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Open Source and information security mailing list archives
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Date: Wed, 1 Jul 2015 17:07:40 +0300 From: Alexey Dobriyan <adobriyan@...il.com> To: Chris Rorvick <chris@...vick.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Linux Kernel <linux-kernel@...r.kernel.org>, Rasmus Villemoes <linux@...musvillemoes.dk> Subject: Re: [PATCH] un-improve strrchr() On Wed, Jul 1, 2015 at 2:52 AM, Chris Rorvick <chris@...vick.com> wrote: > [ resending w/o HTML formatting ] > > On Sun, Jun 28, 2015 at 11:44 AM, Alexey Dobriyan <adobriyan@...il.com> wrote: >> Previous code did 1 branch per character + 1 branch for every character >> in the last path component. Current code does 2 branches per characher >> regardless. > > Shouldn't that be "+ 2 branches for every character in the last path > component"? The structure of the loop is basically the same; you're > just performing fewer iterations if the character is found when > searching from the end. Yes, changelog is inaccurate. It is "1 branch per character + 2 branches per character in the last path component" vs "2 branches per character". Rasmus posted benchmark (obvious rdtsc/strrchr/rdtsc) in private. Speed highly depends on -O2/-Os setting and current mainline code is not uniformly faster at least for me. I'll probably resend with new and improved changelog. -- 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/
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