From owner-cvs-sys Sat Mar 9 11:18:09 1996 Return-Path: owner-cvs-sys Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id LAA17663 for cvs-sys-outgoing; Sat, 9 Mar 1996 11:18:09 -0800 (PST) Received: from GndRsh.aac.dev.com (GndRsh.aac.dev.com [198.145.92.241]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id LAA17658 Sat, 9 Mar 1996 11:18:03 -0800 (PST) Received: (from rgrimes@localhost) by GndRsh.aac.dev.com (8.6.12/8.6.12) id LAA10171; Sat, 9 Mar 1996 11:17:24 -0800 From: "Rodney W. Grimes" Message-Id: <199603091917.LAA10171@GndRsh.aac.dev.com> Subject: Re: cvs commit: src/sys/i386/isa rc.c To: rgrimes@freefall.freebsd.org (Rodney W. Grimes) Date: Sat, 9 Mar 1996 11:17:24 -0800 (PST) Cc: CVS-committers@freefall.freebsd.org, cvs-all@freefall.freebsd.org, cvs-sys@freefall.freebsd.org In-Reply-To: <199603091859.KAA16561@freefall.freebsd.org> from "Rodney W. Grimes" at Mar 9, 96 10:59:02 am X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-cvs-sys@FreeBSD.ORG X-Loop: owner-cvs-sys@FreeBSD.ORG Precedence: bulk > > rgrimes 96/03/09 10:59:02 > > Modified: sys/i386/isa rc.c > Log: > Convert a timeout loop from 100 iterations of 15uS to 50 > iterations of 30uS so that really fast systems stop getting > timeout messages from the Riscom driver. > > Reviewed by: ache, peter@nmti.com (Peter da Silva) > > Revision Changes Path > 1.21 +2 -2 src/sys/i386/isa/rc.c Note that this patch really points to a problem in DELAY(X) for X smaller than 20. Right now the DELAY code does an X=-20 and never really goes into the DELAY loop. It seems that on 133Mhz and faster Pentium systems the assumed overhead time of 20uS is no longer valid and something needs to be done to correct this. This is especially true when calling short DELAY's in a loop since that all ends up running from the internal cache. If you spot DELAY being called in an loop some place with values of 20 or below I suggest that the code be corrected to do what I did here or we are going to see more of these types of problems as system speeds increase. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD