Date: Sun, 14 Mar 1999 15:41:29 +0100 (MET) From: Jean-Marc Zucconi <jmz@FreeBSD.ORG> To: roberto@keltia.freenix.fr Cc: ken@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: cvs commit: src/sys/cam cam_xpt.c Message-ID: <199903141441.PAA71438@qix> In-Reply-To: <19990314133528.A4071@keltia.freenix.fr> (message from Ollivier Robert on Sun, 14 Mar 1999 13:35:28 %2B0100)
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>>>>> Ollivier Robert writes: > According to Kenneth Merry: >> Log: >> Disable tagged queueing for the IBM DCAS drives. These drives have poor >> write performance when tagged queueing is enabled. > Do you call that poor performance ? I have two 4 gig drives and they don't > seem that slow for me... > Seeker 1...Seeker 3...Seeker 2...start 'em...done...done...done... > -------Sequential Output-------- ---Sequential Input-- --Random-- > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks--- > Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU > dcas4 256 2891 37.3 2534 9.8 1797 7.9 5913 48.2 5916 19.2 96.0 3.5 > Writing the 256 Megabyte file, 'iozone.tmp'...95.656250 seconds > Reading the file...43.687500 seconds > IOZONE performance measurements: > 2806251 bytes/second for writing the file > 6144445 bytes/second for reading the file Yes this is very poor for a wide drive. On my narrow DCAS-34330: Writing the 250 Megabyte file, 'iozone.tmp'...80.351562 seconds Reading the file...38.601562 seconds IOZONE performance measurements: 3262463 bytes/second for writing the file 6791020 bytes/second for reading the file da1 at ahc0 bus 0 target 1 lun 0 da1: <IBM DCAS-34330 S65A> Fixed Direct Access SCSI-2 device da1: 20.000MB/s transfers (20.000MHz, offset 15), Tagged Queueing Enabled da1: 4134MB (8467200 512 byte sectors: 255H 63S/T 527C) > ncr0: <ncr 53c875 fast20 wide scsi> rev 0x03 int a irq 9 on pci0.11.0 > da1 at ncr0 bus 0 target 1 lun 0 > da1: <IBM DCAS-34330W S65A> Fixed Direct Access SCSI-2 device > da1: 40.00MB/s transfers (20.00MHz, offset 15, 16bit), Tagged Queueing Enabled > da1: 4134MB (8467200 512 byte sectors: 255H 63S/T 527C) > da0 at ncr0 bus 0 target 0 lun 0 > da0: <IBM DCAS-34330W S65A> Fixed Direct Access SCSI-2 device > da0: 40.00MB/s transfers (20.00MHz, offset 15, 16bit), Tagged Queueing Enabled > da0: 4134MB (8467200 512 byte sectors: 255H 63S/T 527C) Jean-Marc To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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