From owner-freebsd-hackers Mon Apr 1 07:46:22 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id HAA01358 for hackers-outgoing; Mon, 1 Apr 1996 07:46:22 -0800 (PST) Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id HAA01312 for ; Mon, 1 Apr 1996 07:45:50 -0800 (PST) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id RAA23295; Mon, 1 Apr 1996 17:45:05 +0200 From: Luigi Rizzo Message-Id: <199604011545.RAA23295@labinfo.iet.unipi.it> Subject: Re: HDD cpu usage (IDE vs. SCSI). To: davidg@Root.COM Date: Mon, 1 Apr 1996 17:45:05 +0200 (MET DST) Cc: dutchman@spase.nl, freebsd-hackers@freebsd.org In-Reply-To: <199604011030.CAA08362@Root.COM> from "David Greenman" at Apr 1, 96 02:29:59 am X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > >How come the seagate uses twice as much cpu as the quantum? > > Because a Pentium-90 is much faster than a 486-100 for certain things and > most of the %CPU is for total I/O overhead, not just the overhead in the > device driver. Hmmm... if I get it right this means that under certain circumstances (1 disk, onboard IDE controller, medium-fast CPU) using SCSI instead of IDE gives you only a very little saving (which BTW is what I am convinced of, but this has not been the dominating opinion on this list). Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ ====================================================================