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Date: Tue, 20 Oct 2009 08:33:26 +0200 From: Ingo Molnar <mingo@...e.hu> To: Ling Ma <linguranus@...il.com> Cc: "H. Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org Subject: Re: [PATCH RFC] [X86] performance improvement for memcpy_64.S by avoid memory miss predication. * Ling Ma <linguranus@...il.com> wrote: > Hi Ingo > Thanks for your suggestion. I used 'perf stat --repeat 10 > /develop/trunk/memcpy/static' to measure before/after patch. > > The test program I wrote: > for (i = 64; i < 4096 *4; i ++) > do_memcpy(src, dst, i); > > when src offset is 0xbe000, dst is 0xad008, the measured result: > > Before patch: > Performance counter stats for '/develop/trunk/memcpy/static' (10 runs): > <not counted> task-clock-msecs > <not counted> context-switches > <not counted> CPU-migrations > <not counted> page-faults > <not counted> cycles > <not counted> instructions > <not counted> cache-references > <not counted> cache-misses > 37.408743997 seconds time elapsed ( +- 0.222% ) hm, on what kind of CPU have you run this? Why are those events not counting? Is it some older, Pentium-4 alike CPU perhaps? Ingo -- 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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