From owner-cvs-all Mon Dec 24 22:59:50 2001 Delivered-To: cvs-all@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id 461E237B421; Mon, 24 Dec 2001 22:59:38 -0800 (PST) Received: (from dillon@localhost) by apollo.backplane.com (8.11.6/8.9.1) id fBP6xaR33808; Mon, 24 Dec 2001 22:59:36 -0800 (PST) (envelope-from dillon) Date: Mon, 24 Dec 2001 22:59:36 -0800 (PST) From: Matthew Dillon Message-Id: <200112250659.fBP6xaR33808@apollo.backplane.com> To: "M. Warner Losh" Cc: peter.jeremy@alcatel.com.au, phk@critter.freebsd.dk, dg@root.com, bde@zeta.org.au, silby@silby.com, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/dev/sio sio.c References: <20011222193231.D24034@nexus.root.com> <61654.1009097922@critter.freebsd.dk> <20011224162247.B85044@gsmx07.alcatel.com.au> <20011224.234720.15269884.imp@village.org> 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 :However, I have had complaints from a few people that have see silo :overflows on pccard (both with fast interrupts, and slow ones now :basically forced by 4.4). I don't know if the latencies in normal :interrupts will all be solved by the HIGH -> MEDH change (since it :takes us from 2 character times (32us) to 8 character times (128us). At 115200 baud, 8N1, your character rate is 11.52 KHz which is 86.8 uS / character, so the safety limit is 173 uS vs 694 uS assuming a standard 16550A with a 16 character FIFO. :I've seen interrupt latency occasionally be as high as 20-100ms :(depending on the machine we ran it on) for the parallel port (since :I'm measuring pps from an atomic clock with it, we can tell these huge :outliers very easily). : :Warner Latencies that high can probably be traced easily by recording the interrupted program counter, aka Linux, aka Amiga (Amiga did it first. Since the Amiga serial port was a piece of crap they used this trick to track down and fix long interrupt disablements in the OS core). -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message