Date: Thu, 8 Nov 2007 16:52:38 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Randall Hyde <randyhyde@earthlink.net> Cc: freebsd-hackers@freebsd.org Subject: Re: Some FreeBSD performance Issues Message-ID: <20071108225238.GB22005@dan.emsphone.com> In-Reply-To: <000701c82253$b3a8c030$6302a8c0@pentiv> References: <000701c82253$b3a8c030$6302a8c0@pentiv>
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In the last episode (Nov 08), Randall Hyde said: > It appears that character-at-a-time file I/O is *exceptionally* slow. > Yes, I realize that when processing large files I really ought to be > doing block/buffered I/O to get the best performance, but for certain > library routines I've written it's been far more convenient to do > character-at-a-time I/O rather than deal with all the buffering > issues. In the past, while slower, this character-at-a-time paradigm > has provided reasonable, though not stellar, performance under > Windows and Linux. However, with the port to FreeBSD I'm seeing a > three-orders-of-magnitude performance loss. Here's my little test > program: [...] > The "fileio.open" call is basically a bsd.open( "socket.h", bsd.O_RDONLY ); > API call. The socket.h file is about 19K long (it's from the FreeBSD > include file set). In particular, I would draw your attention to the first > two tests that do character-at-a-time I/O. The difference in performance What timings does "dd if=/usr/include/sys/socket.h of=/dev/null ibs=1 obs=64k" report? It takes about .4 sec on my non-idle dual pIII-900 system. Try truss'ing your program as it runs; maybe the program is doing some extra syscalls you aren't aware of? -- Dan Nelson dnelson@allantgroup.com
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