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Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!yarrina.connect.com.au!warrane.connect.com.au!godzilla.zeta.org.au!not-for-mail From: bde@zeta.org.au (Bruce Evans) Newsgroups: comp.os.386bsd.questions Subject: Re: dismal file system performance and odd scsi stuff Date: 2 Nov 1994 10:14:33 +1100 Organization: Kralizec Dialup Unix Sydney - +61-2-837-1183, v.32bis v.42bis Lines: 35 Message-ID: <396i4p$o0@godzilla.zeta.org.au> References: <oigcIge00iUzI28UlV@andrew.cmu.edu> NNTP-Posting-Host: localhost.zeta.org.au In article <oigcIge00iUzI28UlV@andrew.cmu.edu>, Alex R.N. Wetmore <aw2t+@andrew.cmu.edu> wrote: >I'm trying to figure out how to get the best file system performance out of >my system (486sx/25, 250 meg WD IDE, 1gig Micropolis 4110 SCSI w/ AHA1542C). >I know about tunefs, and have even played with it a bit, but can't get iozone >speeds about 400k per second or so (on the SCSI, even worse on the IDE). SCSI >performance is what I'm looking for, since there isn't much on the IDE. > >Is there any way that I can figure out the ideal performance options for a >drive? Should I just play around. I read the chapter on the filesystem in Try "newfs -d 0 -n 1 ..." and the default of "newfs -d 4 ..." and values in between. >This also might be more of a hardware based question. I've noticed that >I get exactly one megabyte per second using dd to read data from my sd0a >device. (I used the command "dd if=/dev/sd0a of=/dev/null bs=4k >count=1024). This seems like a very odd number to get constantly, as if >its being throttled that low for some reason. Is there anything in my It's throttled by the too-small value of 2048 for BLKDEV_IOSIZE in <machine/param.h>. On my system, the U34F SCSI controller seems to take a minumum of 5ms per request, so it is limited to 400K/s through /dev/sd0d and 100K/sec through /dev/rsd0d with a block size of 512 although it can read /dev/rsd0d at 2500K/sec with a block size of 64K. Use the raw device to determine guaranteed-not-to-exceed speeds. I see speeds like the following: max raw speed 2500K/sec iozone 1250K/sec (read) 1700K/sec (write) read 250M file system 600K/sec copy 250M file system 150K/sec throughput copy /usr/share/zoneinfo 15K/sec throughput -- Bruce Evans bde@zeta.org.au