From owner-freebsd-hackers Wed Nov 11 13:47:33 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id NAA06816 for freebsd-hackers-outgoing; Wed, 11 Nov 1998 13:47:33 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from smtp.algonet.se (tomei.algonet.se [194.213.74.114]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id NAA06809 for ; Wed, 11 Nov 1998 13:47:30 -0800 (PST) (envelope-from mal@algonet.se) Received: (qmail 3074 invoked from network); 11 Nov 1998 22:47:09 +0100 Received: from kairos.algonet.se (194.213.74.18) by tomei.algonet.se with SMTP; 11 Nov 1998 22:47:09 +0100 Received: (mal@localhost) by kairos.algonet.se (8.8.8+Sun/8.6.12) id WAA10051; Wed, 11 Nov 1998 22:47:09 +0100 (MET) Date: Wed, 11 Nov 1998 22:47:09 +0100 (MET) Message-Id: <199811112147.WAA10051@kairos.algonet.se> X-Authentication-Warning: kairos.algonet.se: mal set sender to mal@kairos.algonet.se using -f From: Mats Lofkvist To: hackers@FreeBSD.ORG Subject: Re: SCSI vs. DMA33.. References: <199811111842.KAA18548@hub.freebsd.org> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > I must say, I'm surprised. This makes it look like there's more of a > performance hit with concurrent requests on SCSI than on IDE. Let's > look at the performance hits as a percentage (there's some guesswork > which is which, of course, but only a little): > > alone 2 together % drop > wd2 10.2 8.8 14 > wd3 10.0 8.8 12 > da0 5.7 3.3 42 > da1 3.7 2.7 23 Don't know what conclusions to draw, but I don't see this decrease in performance with concurrent requests. Current-smp on a providence mb (7880 on board) with a quantum viking 4.5GB uw (da0) and a vikingII 4.5GB uw (da1): bash# dd if=/dev/rda0c bs=32k count=10000 of=/dev/null 10000+0 records in 10000+0 records out 327680000 bytes transferred in 30.950317 secs (10587291 bytes/sec) bash# dd if=/dev/rda1c bs=32k count=10000 of=/dev/null10000+0 records in 10000+0 records out 327680000 bytes transferred in 23.328261 secs (14046482 bytes/sec) bash# dd if=/dev/rda0c bs=32k count=10000 of=/dev/null & dd if=/dev/rda1c bs=32k count=13000 of=/dev/null [1] 375 13000+0 records in13000+0 records out 425984000 bytes transferred in 30.822861 secs (13820391 bytes/sec) bash# 10000+0 records in 10000+0 records out 327680000 bytes transferred in 31.760830 secs (10317111 bytes/sec) alone 2 together % drop da0 10.6 10.3 1.6 da1 14.0 13.8 2.6 _ Mats Lofkvist mal@algonet.se To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message