From owner-cvs-all Sat Dec 22 19:29: 9 2001 Delivered-To: cvs-all@freebsd.org Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16]) by hub.freebsd.org (Postfix) with ESMTP id 93D7B37B419; Sat, 22 Dec 2001 19:29:02 -0800 (PST) Received: from bde.zeta.org.au (bde.zeta.org.au [203.2.228.102]) by mailman.zeta.org.au (8.9.3/8.8.7) with ESMTP id OAA08748; Sun, 23 Dec 2001 14:28:55 +1100 Date: Sun, 23 Dec 2001 14:29:02 +1100 (EST) From: Bruce Evans X-X-Sender: To: Matthew Dillon Cc: Mike Silbersack , , Subject: Re: cvs commit: src/sys/dev/sio sio.c In-Reply-To: <200112230252.fBN2qVm99224@apollo.backplane.com> Message-ID: <20011223141152.Y10385-100000@gamplex.bde.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Sat, 22 Dec 2001, Matthew Dillon wrote: > I've gone through the logs of sio.c and I see no requirement > that changes be approved by anyone, nor do I see any Approved: > lines in the commit messages. Your backing out of my patch was > totally inappropriate and I have re-committed it. If you don't know who is the author and maintained of this driver then you have no business touching it. > Your explanation is also seriously flawed considering the endemic > problem silo overflows have been over the last few years. If you > want to set the FIFO levels to high, you should first fix the > problems in the system causing the long interrupt delays. Otherwise, > leave it at MEDHI. MEDHI is perfectly reasonable. I fixed the software problems in 386BSD-0.0. Software latency bugs are occasionally reintroduced. -current has several problems in this area. They are mostly design problems so they are hard to fix. However, I think the latency problems in -current only break sio on old machines. IIRC, spinlocks are never held for more than about "only" 2000 (or is it 0x2000) instructions. On a 386/20, 2000 instructions took something like 400 usec, but on not so modern machines (1GHz) it takes more like 4 usec. The driver needs a latency of less than about 75 usec to work for all supported hardware. Most silo overflows seem to be caused by video hardware hogging the bus. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message