From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265922AbTL3UQ7 (ORCPT ); Tue, 30 Dec 2003 15:16:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265923AbTL3UQ7 (ORCPT ); Tue, 30 Dec 2003 15:16:59 -0500 Received: from pirx.hexapodia.org ([65.103.12.242]:20041 "EHLO pirx.hexapodia.org") by vger.kernel.org with ESMTP id S265922AbTL3UQ4 (ORCPT ); Tue, 30 Dec 2003 15:16:56 -0500 Date: Tue, 30 Dec 2003 14:16:55 -0600 From: Andy Isaacson To: linux-kernel@vger.kernel.org Subject: Re: [PATCH] 2.6.0 - Watchdog patches (BK consistency checks) Message-ID: <20031230141655.A30003@hexapodia.org> References: <20030906125136.A9266@infomag.infomag.iguana.be> <20031230004907.GA29143@merlin.emma.line.org> <200312300836.16559.edt@aei.ca> <20031230131350.A32120@hexapodia.org> <20031230195632.GB6992@bounceswoosh.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20031230195632.GB6992@bounceswoosh.org>; from edmudama@mail.bounceswoosh.org on Tue, Dec 30, 2003 at 12:56:32PM -0700 X-PGP-Fingerprint: 48 01 21 E2 D4 E4 68 D1 B8 DF 39 B2 AF A3 16 B9 X-PGP-Key-URL: http://web.hexapodia.org/~adi/pgp.txt X-Domestic-Surveillance: money launder bomb tax evasion Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 30, 2003 at 12:56:32PM -0700, Eric D. Mudama wrote: > On Tue, Dec 30 at 13:13, Andy Isaacson wrote: > >On Tue, Dec 30, 2003 at 08:36:15AM -0500, Ed Tomlinson wrote: > >The consistency check definitely should not take 15 minutes. It should > >be (much) less than 30 seconds. What is the hardware you're running on? > > > >I'm running on an Athlon 2 GHz (XP 2400+) with 512MB and a 7200RPM IDE > >disk, and I can do a complete clone (with full data copy and consistency > >check) of the 2.4 tree in 1:40. That was with cold caches; with the > >sfile copies and "checkout:get", a half-gig isn't enough to cache > >everything. The consistency check is about 19 seconds (bk -r check -acv). > > For what it is worth: > > AMD Duron 950MHz, 768MB RAM > 7200RPM 80GB Quantum Viper IDE drive, 26% full > > phat-penguin:~/src/linux-2.5> time bk -r check -acv > 100% |=================================================================| OK > 42.710u 5.770s 2:04.63 38.8% 0+0k 0+0io 74078pf+0w > > over 2 minutes of wall time, 42 seconds of "user" time... (if I'm reading it right), without primed disk caches. > > The 2nd run, half a minute later: > > phat-penguin:~/src/linux-2.5> time bk -r check -acv > 100% |=================================================================| OK > 41.900u 3.080s 0:45.53 98.7% 0+0k 0+0io 74078pf+0w > > > ...would appear to show that BK's checksumming, on my system, is > constrained near 41 seconds of calculation time, and the difference > between the user and the wall-clock time is basically time spent > waiting for the disk to do all its reads. > > > I guess in that case, it'd be interesting to see what the user and > wall times were for the original poster who reported a 15+ minute > integrity check. That's basically right, except that if you don't have enough memory to keep bk's working set in memory, then you're paging and performance starts to suck. I didn't realize that the cpu-bound portion of the check would scale so closely with CPU speed, but it looks like the scaling is almost dead-on; 18.4/41.9 = .439 950/2000 = .475 So I was wrong to say "less than 30 seconds". "If you have a fast CPU and enough memory", I guess. But the memory matters a lot more than the CPU. -andy