Date: Thu, 24 Oct 2002 08:22:53 -0700 From: Juli Mallett <jmallett@FreeBSD.org> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Dan Nelson <dnelson@allantgroup.com>, Kirk McKusick <mckusick@FreeBSD.org>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/fs/specfs spec_vnops.c src/sys/kern subr_disk.c src/sys/ufs/ffs ffs_snapshot.c Message-ID: <20021024082253.B57679@FreeBSD.org> In-Reply-To: <5892.1035472339@critter.freebsd.dk>; from phk@critter.freebsd.dk on Thu, Oct 24, 2002 at 05:12:19PM %2B0200 References: <20021024145822.GA69650@dan.emsphone.com> <5892.1035472339@critter.freebsd.dk>
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* De: Poul-Henning Kamp <phk@critter.freebsd.dk> [ Data: 2002-10-24 ] [ Subjecte: Re: cvs commit: src/sys/fs/specfs spec_vnops.c src/sys/kern subr_disk.c src/sys/ufs/ffs ffs_snapshot.c ] > In message <20021024145822.GA69650@dan.emsphone.com>, Dan Nelson writes: > >In the last episode (Oct 21), Kirk McKusick said: > >> mckusick 2002/10/21 17:59:49 PDT > >> > >> Modified files: > >> sys/fs/specfs spec_vnops.c > >> sys/kern subr_disk.c > >> sys/ufs/ffs ffs_snapshot.c > >> Log: > >> This checkin reimplements the io-request priority hack in a way > >> that works in the new threaded kernel. It was commented out of > > > >I think this cure is worse than the disease. Background fsck times on > >my system went from 10 minutes to an hour, and niced processes that > >want to do any disk I/O at all run at a glacial speed. Try running > >"nice find /" on an otherwise-idle system, for example. Don't bother > >running anything at nice -20 :) > > I as somewhat afraid of this, and therefore floated the idea that > the pacing should be moved all the way up to physio() so it only > affected niced processes which access raw-devices, but Kirk thought > hitting all disk-access was more logical. > > I can't really make up my mind either way. It means (for me) that checking my 4G disk takes 45 minutes total, and during that time, everything has to use a snapshot, and since fsck is going on, snaplck is constantly being blocked on, and so that means that i go from having a very-bogged-down system for 15 minutes, to a useless and frustrating slothy-but-usable-enough-to-not-deter-me system for 45 minutes... I tended to like it better when it got its job over and done with, without taking up such a large chunk of wall clock time. juli. -- Juli Mallett <jmallett@FreeBSD.org> | FreeBSD: The Power To Serve Will break world for fulltime employment. | finger jmallett@FreeBSD.org http://people.FreeBSD.org/~jmallett/ | Support my FreeBSD hacking! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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