From owner-freebsd-current Mon Dec 20 16:31:44 1999 Delivered-To: freebsd-current@freebsd.org Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by hub.freebsd.org (Postfix) with ESMTP id 0A9E614D0B for ; Mon, 20 Dec 1999 16:31:40 -0800 (PST) (envelope-from grog@freebie.lemis.com) Received: (from grog@localhost) by freebie.lemis.com (8.9.3/8.9.0) id LAA06641; Tue, 21 Dec 1999 11:01:50 +1030 (CST) Date: Tue, 21 Dec 1999 11:01:50 +1030 From: Greg Lehey To: Matthew Dillon Cc: FreeBSD current users Subject: Re: Recent current hangs frequently for 1 to 2 seconds. Message-ID: <19991221110148.N440@freebie.lemis.com> References: <19991219143759.C465@freebie.lemis.com> <199912190416.UAA01125@apollo.backplane.com> <19991221095213.L440@freebie.lemis.com> <199912210019.QAA62510@apollo.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0pre2i In-Reply-To: <199912210019.QAA62510@apollo.backplane.com> WWW-Home-Page: http://www.lemis.com/~grog X-PGP-Fingerprint: 6B 7B C3 8C 61 CD 54 AF 13 24 52 F8 6D A4 95 EF Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Monday, 20 December 1999 at 16:19:06 -0800, Matthew Dillon wrote: > > :Thanks. I've put in the patch, but I'm still seeing the problems. It > :seems to be related to SCSI activity (I'm currently performing a > :backup on a DLT drive, and apart from that very little disk I/O). Any > :other ideas? It seems to me as if the whole system freezes > :(keystrokes don't echo, for example), so possibly something is going > :into splhigh for too long. > : > :Greg > > No, this is very odd. Certainly reading from disk should not > cause any blockages. But DLT & SCSI -- there are lots of possiblities > there. Is the DLT device sharing the same SCSI bus as the > disks? Yes. > I've historically had bad luck with a shared arrangement and now > always put SCSI tape units on their own SCSI bus. For other reasons, I intend to do just this, though I'm not sure it's a good idea: for one thing, I don't have any spare PCI slots, so it will have to be a 1542B. But it will be worth checking. It's possible you might be on to something. I've been running iostat at 1 second intervals, and during the last hang I saw: tty ad2 da1 sa1 cpu tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id 36 142 7.75 95 0.72 0.00 0.00 0 10.00 27 0.27 29 0 9 1 61 21 142 8.00 69 0.54 0.00 0.00 0 0.00 0 0.00 6 0 1 0 93 37 143 8.00 44 0.34 0.00 8.00 3 0.00 0 0.00 5 0 1 1 94 41 142 1.76 106 0.18 16.00 5.25 4 10.00 14 0.13 24 0 18 0 57 15 143 1.98 87 0.17 0.00 0.00 0 10.00 16 0.15 30 0 15 2 54 Note that the stop in tape activity corresponds with a start in disk activity. I'll keep an eye on that and see if it looks the same the next time. > If the SCSI bus is hanging something should show up in the kernel logs > or dmesg output. Right. But there's nothing there. > Another possibility is that the SCSI operation is causing a hangup or > bringing out a bug in the networking somewhere. A lockup for a second > or two could be an indication of packet loss. Haven't there been a > couple of mbuf-related commits recently? It would be something to look > review, anyway. I don't see any evidence of network participation. All the activity here is local. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message