From owner-freebsd-hackers Sun Oct 5 08:31:58 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id IAA25569 for hackers-outgoing; Sun, 5 Oct 1997 08:31:58 -0700 (PDT) Received: from punt-1.mail.demon.net (punt-1c.mail.demon.net [194.217.242.136]) by hub.freebsd.org (8.8.7/8.8.7) with SMTP id IAA25558 for ; Sun, 5 Oct 1997 08:31:53 -0700 (PDT) Received: from fdy2.demon.co.uk ([194.222.102.143]) by punt-1.mail.demon.net id aa1429326; 5 Oct 97 16:23 BST Received: (from rjs@localhost) by fdy2.demon.co.uk (8.8.7/8.6.12) id LAA00326; Sun, 5 Oct 1997 11:35:25 +0100 (BST) Date: Sun, 5 Oct 1997 11:35:25 +0100 (BST) From: Robert Swindells Message-Id: <199710051035.LAA00326@fdy2.demon.co.uk> To: babkin@hq.icb.chel.su CC: hackers@freebsd.org In-reply-to: <199710050539.LAA09048@hq.icb.chel.su> (babkin@hq.icb.chel.su) Subject: Re: PCI slowness ? Sender: owner-freebsd-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > The chipset is Intel Triton on some chineese motherboard > with 75MHz Pentium, memory is 60ns EDO. > Theoretical PCI throughput is 33M > of 4-byte transfers per second (the card claims to work > in burst mode). Theoretical memory throughput is at least > 10M of 4-byte transfers per second if we suppose that > the memory cycle with all overhead is 100ns and the > card reads by 4 bytes at a time. But the experiment > shows throughput of only 17MBps or 4.25M of 4 byte > transfers. Does the processor eats all the remaining > throughput (although I think it must load most of the > code it runs at idling into the cache) ? I thought that a 75MHz Pentium ran the PCI bus at 25MHz, not 33MHz. Are you sure that the bus on your system is at 33MHz ? ------------------------------------- Robert Swindells - GenRad Ltd rjs@genrad.co.uk - Work rjs@fdy2.demon.co.uk - Home