Date: Fri, 09 May 2003 09:29:53 +0200 From: "Ian Freislich" <ianf@za.uu.net> To: Bruce Evans <bde@zeta.org.au> Cc: FreeBSD-gnats-submit@freebsd.org Subject: Re: kern/51982: sio1: interrupt-level buffer overflows Message-ID: <55435.1052465393@wcom.com> In-Reply-To: Your message of "Fri, 09 May 2003 09:56:39 %2B1000." <20030509092253.Y61808@gamplex.bde.org> References: <20030509092253.Y61808@gamplex.bde.org>
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Bruce Evans wrote: > On Mon, 5 May 2003, Ian Freislich wrote: > > > >Description: > > Transferring data at "high" speed 115200bps over the serial > > line (even though the actual incoming line stream is about > > 37000bps according to the modem LCD panel) results in the > > following messages on the console at a rate of about 1 log > > line every 10 to 15 seconds. > > > > These buffer overruns have gradually become more frequent > > from about 3 lines and 24 overruns a day around September > > 2002 (when I started running Current - 4.x does not suffer > > from this) to the current flurry. > > -current has excessive interrupt latency caused by Giant locking almost > everything. > > Try changing this line in sio.c: > > cp4ticks = speed / 10 / hz * 4; > > to something like: > > cp4ticks = speed / 10 / hz * 40; Thanks. Making this change seems to have fixed the problem. Will this be committed or do I need to maintain this privately until the larger interrupt latency problem is fixed? > Transient interrupt latency problems are supposed to be made harmless > by using rts flow control. There is a PR (maybe from you?) about rts > flow control apparently not working for one modem. Not me. Ian
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