From owner-freebsd-scsi Tue Aug 24 3:24:37 1999 Delivered-To: freebsd-scsi@freebsd.org Received: from mrelay.jrc.it (mrelay.jrc.it [139.191.1.65]) by hub.freebsd.org (Postfix) with ESMTP id EB54114D85 for ; Tue, 24 Aug 1999 03:24:33 -0700 (PDT) (envelope-from nick.hibma@jrc.it) Received: from elect8 (elect8.jrc.it [139.191.71.152]) by mrelay.jrc.it (LMC5692) with SMTP id MAA02244; Tue, 24 Aug 1999 12:24:07 +0200 (MET DST) Date: Tue, 24 Aug 1999 12:23:53 +0200 (MET DST) From: Nick Hibma X-Sender: n_hibma@elect8 Reply-To: Nick Hibma To: David Greenman Cc: liudong , freebsd-scsi@FreeBSD.ORG Subject: Re: The I/O is too slow than linux In-Reply-To: <199908241005.DAA14184@implode.root.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On a 3.2 machine here: bash-2.03# time dd if=/dev/da0 of=/dev/null count=128000 128000+0 records in 128000+0 records out 65536000 bytes transferred in 19.586158 secs (3346037 bytes/sec) real 0m19.602s user 0m0.242s sys 0m3.602s bash-2.03# time dd if=/dev/rda0 of=/dev/null count=1000 bs=64k 1000+0 records in 1000+0 records out 65536000 bytes transferred in 7.724508 secs (8484165 bytes/sec) real 0m7.749s user 0m0.015s sys 0m0.060s Quite a difference. Linux adapts the blocksize to the read size? Does their implementation of dd do something funny? Nick ahc0: rev 0x03 int a irq 12 on pci0.10.0 da0 at ahc0 bus 0 target 1 lun 0 da0: Fixed Direct Access SCSI-2 device da0: 10.000MB/s transfers (10.000MHz, offset 15), Tagged Queueing Enabled da0: 4340MB (8888924 512 byte sectors: 255H 63S/T 553C) On Tue, 24 Aug 1999, David Greenman wrote: > >then run ... > ># time dd if=/dev/da0 of=/dev/null count=200000 > >200000+0 records in > >200000+0 records out > >102400000 bytes transferred in 36.852771 secs (2778624 bytes/sec) > > > >real 0m36.911s > >user 0m0.372s > >sys 0m5.982s > > You need to use the raw device for tests like this and you should specify > a blocksize as well, e.g.: > > time dd if/dev/rda0 of=/dev/null bs=64k count=200000 > > The block device should only be used when mounting the filesystem. > > -DG > > David Greenman > Co-founder/Principal Architect, The FreeBSD Project - http://www.freebsd.org > Creator of high-performance Internet servers - http://www.terasolutions.com > Pave the road of life with opportunities. > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-scsi" in the body of the message > > -- ISIS/STA, T.P.270, Joint Research Centre, 21020 Ispra, Italy To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message