Date: Fri, 29 Nov 1996 23:44:08 -0500 (EST) From: "John S. Dyson" <toor@dyson.iquest.net> To: mango@staff.communique.net (Raul Zighelboim) Cc: hackers@freefall.freebsd.org, hardware@freefall.freebsd.org Subject: Re: Adaptec UW controller and Seagate Elite performance ? Message-ID: <199611300444.XAA09675@dyson.iquest.net> In-Reply-To: <c=US%a=_%p=Communique._Inc.%l=KAORI-961130042812Z-340@kaori.communique.net> from "Raul Zighelboim" at Nov 29, 96 10:28:12 pm
next in thread | previous in thread | raw e-mail | index | archive | help
> > # bonnie -s 40 (akira, http running) > -------Sequential Output-------- ---Sequential Input-- --Random-- > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks--- > MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU > 40 3271 34.8 3085 13.0 1559 8.3 10330 97.1 44763 95.7 991.0 20.4 > > and > IOZONE performance measurements: > 2039008 bytes/second for writing the file > 34861747 bytes/second for reading the file > > It bothered me that: > 1- reading is 20 times faster than writing You are seeing the results of caching. The system remembers what is written so that it doesn't have to unnecessarily re-read the data. > > 2- 2Mbytes/s for writing seems slow, even if this was a scsi-2 and not > an > scsi fast and wide drive. > I don't know why your iozone write perf is so slow, unless you are writing 512 bytes at a time. Note also, that you might not have the write behind caching enabled on your drive. Try the following commands: # iozone auto and # iozone 40 8192 and # iozone <size-of-memory*2> 8192 and let me know the results. John dyson@freebsd.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199611300444.XAA09675>