From owner-freebsd-hardware Fri Feb 21 00:05:13 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id AAA12700 for hardware-outgoing; Fri, 21 Feb 1997 00:05:13 -0800 (PST) Received: from foo.primenet.com (ip204.sjc.primenet.com [206.165.96.204]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id AAA12695 for ; Fri, 21 Feb 1997 00:05:10 -0800 (PST) Received: (from bkogawa@localhost) by foo.primenet.com (8.8.2/8.6.12) id AAA22530; Fri, 21 Feb 1997 00:05:49 -0800 (PST) Date: Fri, 21 Feb 1997 00:05:49 -0800 (PST) Message-Id: <199702210805.AAA22530@foo.primenet.com> To: bde@zeta.org.au Subject: Re: _big_ IDE disks? Newsgroups: localhost.freebsd.hardware References: <> <199702210543.QAA29486@godzilla.zeta.org.au> From: "Bryan K. Ogawa" Cc: hardware@freebsd.org, bde@zeta.org.au, dkelly@hiwaay.net X-Newsreader: NN version 6.5.0 #1 (NOV) Sender: owner-hardware@freebsd.org X-Loop: FreeBSD.org Precedence: bulk In localhost.freebsd.hardware you write: >>> Run `dd if=/dev/zero of=/dev/null bs=1m count=1000' and complain if >>> the throughtput is much lower than 120MB/sec. [...] >My comment only applies to P5's with a 66MHz memory bus. The speed should >be much the same for CPU speeds of 100MHz and larger multiples of 33[.3]MHz. >The above dd command essentially copies the same 4K kernel buffer to >sequential memory 256 times. . The kernel buffer stays in the L1 cache >so reading it is almost free and the speed approaches the maximum main >memory write speed which is 133M * 4/3 on my P5/133 (I think it is for >a 6-2-2-2 burst cycle). Hm. I can only get about 100MB/seg doing this, max (P5/133). I did it with an X server running--should that matter? {foo} ~ 0:01 ttyp3 > uname -a FreeBSD foo.primenet.com 2.2-ALPHA FreeBSD 2.2-ALPHA #5: Sun Jan 12 19:28:01 PST 1997 bkogawa@foo.primenet.com:/usr/src/sys/compile/ATWO i386 {foo} ~ 0:04 ttyp3 > dd if=/dev/zero of=/dev/null bs=1m count=1000 1000+0 records in 1000+0 records out 1048576000 bytes transferred in 10 secs (104857600 bytes/sec) Perhaps my BIOS is mis-set, but I wouldn't think so...? -- bryan k ogawa http://www.primenet.com/~bkogawa/