Date: Wed, 11 Jul 2007 22:43:16 +0200 From: Roman Divacky <rdivacky@FreeBSD.org> To: "Sean C. Farley" <scf@FreeBSD.org> Cc: freebsd-arch@FreeBSD.org Subject: Re: Assembly string functions in i386 libc Message-ID: <20070711204315.GA49688@freebsd.org> In-Reply-To: <20070711134721.D2385@thor.farley.org> References: <20070711134721.D2385@thor.farley.org>
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On Wed, Jul 11, 2007 at 03:24:01PM -0500, Sean C. Farley wrote: > While looking at increasing the speed of strlen(), I noticed that on > i386 platforms (PIII, P4 and Athlon XP) the performance is abysmal in > libc compared to the version I was writing. After more testing, I found > it was only the assembly version that is really slow. The C version is > fairly quick. Is there a need to continue to use the assembly versions > of string functions on i386? Does it mainly help slower systems such as > those with i386 or i486 CPU's? > > I have the results from my P4 (Id = 0xf24 Stepping = 4) system and the > test program here[1]. strlen.tar.bz2 is the archive of it for anyone's > testing. In the strlen/results subdirectory, there are the results for > strings of increasing lengths. just to state facts... glibc 2.3.6 uses almost exactly the same asm code for i386 (cld;repn[ez] scasb)
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