From owner-freebsd-current@FreeBSD.ORG Wed Apr 27 23:44:13 2011 Return-Path: Delivered-To: current@FreeBSD.org Received: from mx2.freebsd.org (mx2.freebsd.org [IPv6:2001:4f8:fff6::35]) by hub.freebsd.org (Postfix) with ESMTP id 1424B1065670; Wed, 27 Apr 2011 23:44:13 +0000 (UTC) (envelope-from dougb@FreeBSD.org) Received: from 65-241-43-5.globalsuite.net (hub.freebsd.org [IPv6:2001:4f8:fff6::36]) by mx2.freebsd.org (Postfix) with ESMTP id 3535415377B; Wed, 27 Apr 2011 23:44:12 +0000 (UTC) Message-ID: <4DB8AA4B.1070502@FreeBSD.org> Date: Wed, 27 Apr 2011 16:44:11 -0700 From: Doug Barton Organization: http://SupersetSolutions.com/ User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.15) Gecko/20110319 Thunderbird/3.1.9 MIME-Version: 1.0 To: Alexander Best References: <4DB620CB.50302@FreeBSD.org> <20110426103741.GA25031@freebsd.org> In-Reply-To: <20110426103741.GA25031@freebsd.org> X-Enigmail-Version: 1.1.2 OpenPGP: id=1A1ABC84 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Steve Wills , Alexander Motin , current@FreeBSD.org Subject: Re: responsiveness during IO tasks X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 Apr 2011 23:44:13 -0000 On 04/26/2011 03:37, Alexander Best wrote: > On Mon Apr 25 11, Steve Wills wrote: > Hi, > > I've noticed lately that when doing heavy IO, my 9-CURRENT system (Fri > Apr 15 23:33:46 EDT 2011) is quite unresponsive. I have two ZFS mirrors > setup and run KDE4. The system has 12GB of RAM. > > When I, for example, copy an ISO image from one mirror to the other, the > whole desktop becomes really slow during the copy. It takes a good 15 > seconds to open a new tab in Konsole, switching windows takes a while, > etc. Once the copy is finished, things are fine. It wasn't like this > back before I upgraded from 8.2-RC1 to 9-CURRENT. Has anyone else > noticed something similar, or is it just me? Is there any other info I > can provide or something I should look for? > >> i've noticed this too. for me the situation is sometimes even worse. during >> heavy i/o the mouse cursor won't even respond. > >> i think this is a scheduler isse. maybe running a non-preemptive kernel or >> switching to the old 4bsd scheduler fixes it? Try backing up your src tree to r212540, clean /usr/obj, buildworld/kernel and see if that helps. I just tracked down a big part of my current problem (pun intended) to r212541, the one-shot timer commit. I'm working on a larger post to describe my problems, but short version is, up through r212540 I can load the system down as heavily as I want, and while there may be some unresponsiveness it's at least stable. If I update to one-shot timers the system wedges as soon as I put load on it. No panic, not even a reboot, it just wedges solid requiring it to be powered off. You should also test SCHED_4BSD to see if that improves your situation. There have been a lot of reports about problems with SCHED_ULE with heavy disk i/o. Moving to 4bsd helps me in terms of interactivity, but I needed to find the crashing problem first. hth, Doug (sorry mav) -- Nothin' ever doesn't change, but nothin' changes much. -- OK Go Breadth of IT experience, and depth of knowledge in the DNS. Yours for the right price. :) http://SupersetSolutions.com/