Date: Sun, 23 Dec 2001 14:29:02 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Mike Silbersack <silby@silby.com>, <cvs-committers@FreeBSD.ORG>, <cvs-all@FreeBSD.ORG> Subject: Re: cvs commit: src/sys/dev/sio sio.c Message-ID: <20011223141152.Y10385-100000@gamplex.bde.org> In-Reply-To: <200112230252.fBN2qVm99224@apollo.backplane.com>
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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
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