Date: Wed, 18 Aug 2010 23:12:31 +0200 From: Dimitry Andric <dimitry@andric.com> To: Peter Jeremy <peterjeremy@acm.org> Cc: Alan Cox <alan.l.cox@gmail.com>, current@freebsd.org Subject: Re: Official request: Please make GNU grep the default Message-ID: <4C6C4CBF.1040200@andric.com> In-Reply-To: <20100818205206.GA55620@server.vk2pj.dyndns.org> References: <4C673F02.8000805@FreeBSD.org> <20100815013438.GA8958@troutmask.apl.washington.edu> <4C67492C.5020206@FreeBSD.org> <B7A05068-9578-4341-851B-86BD9BC7A2DA@gmail.com> <8639ufd78w.fsf@ds4.des.no> <4C6844D8.5070602@andric.com> <86sk2faqdl.fsf@ds4.des.no> <4C6AAA88.5080606@andric.com> <AANLkTik-ee6iKiOoA=KMmmToS2giUOmW5JB-d1vBx9r3@mail.gmail.com> <4C6AF13A.1080606@andric.com> <20100818205206.GA55620@server.vk2pj.dyndns.org>
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On 2010-08-18 22:52, Peter Jeremy wrote: >> grep with normal mmap() 1396s >> grep with prefault mmap() 1354s >> grep with regular read() 1354s > > Is this with uncached (ie remount the filesystem on each test) or cached > data? This is all on the same filesystem, and the test file is ~370MB, so eventually all data will be in RAM, most likely. E.g. normal mmap() seems to add a bit of overhead that explains the slower result. > Which filesystem (and does it change for different filesystems > (particularly between UFS and ZFS))? I only checked on UFS2. > And one trial is not statistically valid - especially given the small > differences. How about multiple multiple trials with ministat. The result were averages of three trials; they were fairly close to each other, but I didn't calculate the standard deviation. I was not aware of ministat, which looks like a real handy program. :)
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