From owner-freebsd-bugs@FreeBSD.ORG Sat Jun 4 11:50:05 2005 Return-Path: X-Original-To: freebsd-bugs@hub.freebsd.org Delivered-To: freebsd-bugs@hub.freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DDA3916A41C for ; Sat, 4 Jun 2005 11:50:05 +0000 (GMT) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [216.136.204.21]) by mx1.FreeBSD.org (Postfix) with ESMTP id B70D343D1D for ; Sat, 4 Jun 2005 11:50:05 +0000 (GMT) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (gnats@localhost [127.0.0.1]) by freefall.freebsd.org (8.13.3/8.13.3) with ESMTP id j54Bo5Xw035146 for ; Sat, 4 Jun 2005 11:50:05 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.13.3/8.13.1/Submit) id j54Bo5ZR035145; Sat, 4 Jun 2005 11:50:05 GMT (envelope-from gnats) Date: Sat, 4 Jun 2005 11:50:05 GMT Message-Id: <200506041150.j54Bo5ZR035145@freefall.freebsd.org> To: freebsd-bugs@FreeBSD.org From: Bruce Evans Cc: Subject: Re: kern/81807: Silo overflows with serial multiport cards X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Bruce Evans List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 04 Jun 2005 11:50:06 -0000 The following reply was made to PR kern/81807; it has been noted by GNATS. From: Bruce Evans To: Bernd Luevelsmeyer Cc: FreeBSD-gnats-submit@FreeBSD.org, freebsd-bugs@FreeBSD.org Subject: Re: kern/81807: Silo overflows with serial multiport cards Date: Sat, 4 Jun 2005 21:44:14 +1000 (EST) On Thu, 2 Jun 2005, Bernd Luevelsmeyer wrote: >> Description: > The machine has 3 serial 8-port-cards installed, 2 of them ISA cards > and one PCI card. The card model of all 3 of them is Moxa SmartIO > C168H (http://www.moxa.com/Product/C168H.htm and > http://www.moxa.com/Product/C168HPCI.htm). Since Upgrading to > 5-Stable the ISA cards have high numbers of silo overflows. This did > not happen with 4-Stable. > The overflows happened with SCHED_4BSD or SCHED_ULE, with and > without PREEMPTION in the kernel, and regardless of baudrate (I > tried 9600 and 115200). Also I tried several HZ values in the kernel > (100, 1000 and 4000), and it didn't matter. > > The machine is a PII with 300 MHz. Now this isn't the most powerful > (and ISA is a little bit old-fashioned), but the effect happens also > when only one of the 24 ports is used and it's at 9600 Baud, and > anyway with 4-Stable there was no problem at all. Interrupt handling is bad in -current but not usually that bad. The loss of performance was in the 5-10% range when I tested it a lot on a 366 MHz Celeron 12-18 months ago. Latency increase is worse than performance decrease but wasn't noticeable with <= 8 ports at 115200. > Here is the machine's dmesg: Everything seems to be set up correctly. sio even handles the isa ports better that the pci ports. I would have expected silo overflows to occur for the pci ports first because fast interrupts are not used for them (try using the PUC_FASTINTR option to fix this). Interrupts seem to be working at probe time. Do they work later? Use vmstat or systat -v to check that some keep occurring. Check that fast interrupts are used by booting with -v. Bruce