Date: Fri, 06 Jun 2008 00:25:39 +0200 From: Kris Kennaway <kris@FreeBSD.org> To: Kirk Strauser <kirk@strauser.com> Cc: freebsd-questions@freebsd.org Subject: Re: Poor read() performance, and I can't profile it Message-ID: <484867E3.3070705@FreeBSD.org> In-Reply-To: <200806051617.54400.kirk@strauser.com> References: <200806051508.29424.kirk@strauser.com> <4848523E.2010604@FreeBSD.org> <200806051617.54400.kirk@strauser.com>
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Kirk Strauser wrote: > On Thursday 05 June 2008, Kris Kennaway wrote: >> Kirk Strauser wrote: > >> ktrace(1) and check for the buffer size in use. It is probably too >> small. >> >> Kris > > It seems to be doing a lot of read()s with 4096-byte buffers. Is that what > you mean? It's also doing a lot of lseek()s to what is likely the current > position anyway (example: seek to 0x00, read 16 bytes, seek to 0x10, etc.). > Would that make a difference, or should that be a NOP? No, if it's reading in 16 byte units it will explain the terrible performance. Kris
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