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
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