Date: Sun, 22 Feb 2009 23:20:55 +0100 (CET) From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> To: Junsuk Shin <junsukshin@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: read two files simultaneously Message-ID: <20090222232034.O66317@wojtek.tensor.gdynia.pl> In-Reply-To: <7873ac110902221044hfd96a8cn5b32e0f90edca212@mail.gmail.com> References: <7873ac110902211146k6a8ee7d0pd67edc559ed14b15@mail.gmail.com> <20090221235530.C60480@wojtek.tensor.gdynia.pl> <7873ac110902221044hfd96a8cn5b32e0f90edca212@mail.gmail.com>
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> That's true. Using bigger buffer will help, but it doesn't tell why reading > large size file is slower than reading small size file. > really slower? or just bigger difference with large files? > > On Sat, Feb 21, 2009 at 5:56 PM, Wojciech Puchar < > wojtek@wojtek.tensor.gdynia.pl> wrote: > >> I'm just guessing inode structure, the physical file location on HDD >>> might be related to this. But, if I read only one file, the size >>> doesn't matter. Reading file (10M, 100M, 700M) gives constantly about >>> 70MB/s, and the weird thing happens when I read 2 files of big size. >>> >> >> if you use O_DIRECT it's read from disk exactly as you specified, without >> readahead, so you do a lot of seeks. >> >> simply use bigger buffer like 1MB >> > > > > -- > Junsuk >
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