Date: Thu, 30 Aug 2001 03:15:21 -0500 From: Mike Meyer <mwm@mired.org> To: "Kory Hamzeh" <kory@avatar.com> Cc: questions@freebsd.org Subject: RE: Performance tuning results Message-ID: <15245.63001.898491.751110@guru.mired.org> In-Reply-To: <33531376@toto.iv>
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Kory Hamzeh <kory@avatar.com> types: > The Benchmark: I have a shell script that converts about 650 JPG files with > an average size of 30K to JPG thumbnails with an average size of 8K. I > rebooted the system before each test and entered the exact same commands. I > used the "time" command and just recorded the total elapsed time. There are some real disk benchmarks in the ports tree. You might check those out. > Results: > > IDE write caching off, softupdates off: 51.97 secs > IDE Write caching on, softupdates off: 47.39 secs > IDE Write caching off, softupdates on: 50.46 secs > IDE Write caching on, softupdates on: 47.32 secs > > What's interesting is that IDE write caching helped more than the > softupdates. Why is that interesting? Softupdates caches things in the system memory to try and improve performance in a reliable manner. IDE disk caching caches things in the disks memory without worrying about reliability. One would expect the more reliable mechanism to be slower. If you really want the extra speed - and don't care about reliability - you can mount your file systems async, softupdates off. If soft udpates are on, the async flag to mount is quietly ignored. That caches data in the system memory without regard to reliability just like the IDE disk cache does. <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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