From owner-freebsd-hackers Sun Oct 20 0:19:43 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BC46B37B401 for ; Sun, 20 Oct 2002 00:19:42 -0700 (PDT) Received: from HAL9000.homeunix.com (12-232-220-15.client.attbi.com [12.232.220.15]) by mx1.FreeBSD.org (Postfix) with ESMTP id D3DA843E9E for ; Sun, 20 Oct 2002 00:19:36 -0700 (PDT) (envelope-from dschultz@uclink.Berkeley.EDU) Received: from HAL9000.homeunix.com (localhost [127.0.0.1]) by HAL9000.homeunix.com (8.12.6/8.12.5) with ESMTP id g9K7JVjf024805; Sun, 20 Oct 2002 00:19:32 -0700 (PDT) (envelope-from dschultz@uclink.Berkeley.EDU) Received: (from das@localhost) by HAL9000.homeunix.com (8.12.6/8.12.5/Submit) id g9K7JUsL024804; Sun, 20 Oct 2002 00:19:30 -0700 (PDT) (envelope-from dschultz@uclink.Berkeley.EDU) Date: Sun, 20 Oct 2002 00:19:30 -0700 From: David Schultz To: Dan Nelson Cc: Terry Lambert , Brooks Davis , hackers@FreeBSD.ORG Subject: Re: adding a delay before background fsck Message-ID: <20021020071930.GA24660@HAL9000.homeunix.com> Mail-Followup-To: Dan Nelson , Terry Lambert , Brooks Davis , hackers@FreeBSD.ORG References: <20021019223250.A14311@Odin.AC.HMC.Edu> <3DB25030.20DC0624@mindspring.com> <20021020065635.GB66757@dan.emsphone.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20021020065635.GB66757@dan.emsphone.com> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Thus spake Dan Nelson : > In the last episode (Oct 19), Terry Lambert said: > > Brooks Davis wrote: > > > Please comment on the following patch to add a delay before > > > starting background fsck. The issues this addresses is that it > > > takes a long time to start X or other large apps like mozilla while > > > a background fsck is running (at least on my laptop). Once they > > > are up and in cache, performance is slightly bumpy, but acceptable. > > > Thus, being able to set a delay (I use 120s) to allow those > > > applications to be started, makes background fsck much more useful. > > > I suspect this feature would also be useful in aiding recover on > > > servers. > > > > Shouldn't running it at idleprio "just work"? > > Unfortunately, priorities do not apply to I/O. `Nice' values *do* apply to I/O in -CURRENT. Specifically, if a process with a positive nice value attempts to do disk I/O while there are other outstanding requests, it is put to sleep for p_nice/HZ seconds. I think this feature was added specifically for background fsck. If performance is a problem, perhaps it is the nice value that needs to be tuned. See Kirk's BSDCon paper on snapshots for details. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message