From: Hans Reiser <reiser@namesys.com>
To: Rik van Riel <riel@conectiva.com.br>
Cc: Christoph Hellwig <hch@caldera.de>, linux-kernel@vger.kernel.org
Subject: Re: ReiserFS / 2.4.6 / Data Corruption
Date: Tue, 31 Jul 2001 03:12:38 +0400 [thread overview]
Message-ID: <3B65E9E6.E6444256@namesys.com> (raw)
In-Reply-To: <Pine.LNX.4.33L.0107301946380.5582-100000@duckman.distro.conectiva>
Rik van Riel wrote:
> > If you could halve linux memory manager performance and check as
> > many things as reiserfs checks, would you do it.
>
> I haven't removed a single debugging check from the
> 2.4 VM. Performance is MUCH more reliant on things
> like evicting the right page from RAM or reading in
> the right page at the right time.
>
> CPU usage is only secondary.
>
> > .. You made the right choice.
>
> Thanks ;) [yeah, yeah ... flame me about out-of-context]
>
> > Now, if you add a #define, you can check as many things as
> > ReiserFS checks, and still go just as fast....
>
> I'm sure these checks make reiserfs a tad more CPU hungry,
> but isn't the real win in reiserfs supposed to come from
> superior disk layout, readahead across files, etc... ?
>
> Or is that all just a myth ?
>
> regards,
>
> Rik
> --
> Executive summary of a recent Microsoft press release:
> "we are concerned about the GNU General Public License (GPL)"
>
> http://www.surriel.com/
> http://www.conectiva.com/ http://distro.conectiva.com/
A tree is a complex structure. You can check it, and the temporary structures
involved in balancing it, quite a lot of ways while balancing it. I believe you
that the checks you need for your code have no significant performance impact.
Ours sometimes do. Consistency checks can be quite a bit more than a tad
consumptive of CPU. Like I said, there were a few checks we removed after the
bug was gone because we got tired waiting for our debugging iterations taking so
long because of them.
Using the #define means we don't have to think about the effect on performance
of a check, we just leave it in. Some checks belong outside the #define
(checking to see if garbage came back from disk is left outside the define
nowadays.) Distros should trust the developers in these tradeoff decisions.
Otherwise, things just get stupid.
Hans
next prev parent reply other threads:[~2001-07-30 23:12 UTC|newest]
Thread overview: 140+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-07-18 4:14 ReiserFS / 2.4.6 / Data Corruption Sam Thompson
2001-07-18 5:18 ` Steve Kieu
2001-07-18 16:22 ` Erik Mouw
2001-07-19 2:02 ` Steve Kieu
2001-07-19 13:28 ` Hans Reiser
2001-07-19 15:50 ` Erik Mouw
2001-07-27 12:52 ` bvermeul
2001-07-27 12:55 ` Hans Reiser
2001-07-27 13:24 ` bvermeul
2001-07-27 14:18 ` Joshua Schmidlkofer
2001-07-27 14:55 ` Hans Reiser
2001-07-27 15:02 ` Chris Wedgwood
2001-07-27 16:06 ` Henning P. Schmiedehausen
2001-07-27 22:02 ` Luigi Genoni
2001-07-28 13:45 ` Matthew Gardiner
2001-07-28 16:15 ` Hans Reiser
2001-07-28 16:45 ` Marcus Meissner
2001-07-28 16:45 ` Christoph Hellwig
2001-07-29 10:19 ` Matthew Gardiner
2001-07-29 11:04 ` Chris Wedgwood
2001-07-30 10:08 ` Hans Reiser
2001-07-30 19:06 ` Christoph Hellwig
2001-07-30 20:30 ` Hans Reiser
2001-07-30 20:49 ` Christoph Hellwig
2001-07-30 21:05 ` Hans Reiser
2001-07-30 21:29 ` Christoph Hellwig
2001-07-30 21:44 ` Hans Reiser
2001-07-30 21:48 ` Hans Reiser
2001-07-30 21:57 ` Chris Wedgwood
2001-07-30 21:58 ` Christoph Hellwig
2001-07-31 7:45 ` Henning P. Schmiedehausen
2001-07-31 9:55 ` Hans Reiser
2001-07-31 10:24 ` Arjan van de Ven
2001-07-31 10:24 ` Anders Eriksson
2001-07-31 10:32 ` Chris Wedgwood
2001-07-31 17:01 ` [OT] " J Sloan
2001-07-30 21:59 ` Rik van Riel
2001-07-30 22:34 ` Hans Reiser
2001-07-31 11:34 ` David Weinehall
2001-07-31 12:22 ` ReiserFS / 2.4.6 / Data Corruption (patch to cause redhat to unmount reiserfs on halt included) Hans Reiser
2001-07-31 12:37 ` Christoph Hellwig
2001-07-31 13:12 ` Hans Reiser
2001-07-30 22:41 ` ReiserFS / 2.4.6 / Data Corruption Kip Macy
2001-07-30 22:50 ` Christoph Hellwig
2001-07-30 21:13 ` Hans Reiser
2001-07-30 21:21 ` Hans Reiser
2001-07-30 21:49 ` Christoph Hellwig
2001-07-31 2:34 ` Andrew Morton
2001-07-30 22:04 ` Rik van Riel
2001-07-30 22:36 ` Hans Reiser
2001-07-30 22:53 ` Rik van Riel
2001-07-30 23:12 ` Hans Reiser [this message]
2001-07-31 10:32 ` Chris Wedgwood
2001-07-31 10:59 ` Hans Reiser
2001-07-31 11:42 ` Chris Wedgwood
2001-07-31 13:41 ` Chris Mason
2001-07-31 15:15 ` Chris Wedgwood
2001-07-31 15:58 ` Chris Mason
2001-07-31 15:22 ` Hans Reiser
2001-07-31 15:49 ` Chris Mason
2001-07-31 22:08 ` Jussi Laako
2001-07-31 22:32 ` Dan Hollis
2001-07-31 23:45 ` Chris Wedgwood
2001-08-05 22:19 ` CRC loop method (was Re: ReiserFS / 2.4.6 / Data Corruption) Pavel Machek
2001-08-01 16:23 ` ReiserFS / 2.4.6 / Data Corruption Andreas Dilger
2001-08-02 13:44 ` Pavel Machek
2001-07-27 15:06 ` Daniel Phillips
2001-07-27 15:33 ` Hans Reiser
2001-07-27 16:30 ` Daniel Phillips
2001-07-27 16:49 ` Early Flush Hans Reiser
2001-07-27 15:07 ` ReiserFS / 2.4.6 / Data Corruption Chris Wedgwood
2001-07-27 16:39 ` Andrew Morton
2001-07-27 16:57 ` Hans Reiser
2001-07-27 17:28 ` Andrew Morton
2001-07-27 17:45 ` Hans Reiser
2001-07-27 17:10 ` Steve Lord
2001-07-27 14:48 ` Hans Reiser
2001-07-27 15:04 ` bvermeul
2001-07-27 15:38 ` Hans Reiser
2001-07-27 17:29 ` Eric W. Biederman
2001-07-27 18:47 ` bvermeul
2001-07-27 19:22 ` Hans Reiser
2001-07-28 6:19 ` bvermeul
2001-07-28 7:39 ` Hans Reiser
2001-07-27 19:30 ` Jussi Laako
2001-07-28 6:21 ` bvermeul
2001-07-27 21:49 ` Daniel Phillips
2001-07-27 20:49 ` Lehmann
2001-07-28 14:13 ` Matthew Gardiner
2001-07-28 14:40 ` bvermeul
2001-07-18 9:42 ` Hans Reiser
[not found] ` <3B5579E7.5090107@namesys.com>
2001-07-18 16:26 ` Sam Thompson
2001-07-18 16:34 ` Hans Reiser
2001-07-18 13:09 ` Andre Pang
[not found] <no.id>
2001-07-27 13:27 ` Alan Cox
2001-07-27 13:38 ` bvermeul
2001-07-27 13:39 ` Alan Cox
2001-07-27 13:47 ` bvermeul
2001-07-27 13:49 ` Alan Cox
2001-07-28 14:16 ` Matthew Gardiner
2001-08-08 18:42 ` Stephen C. Tweedie
2001-07-27 14:16 ` Philip R. Auld
2001-07-27 14:38 ` Jordan
2001-07-27 14:51 ` Hans Reiser
2001-07-27 15:12 ` Philip R. Auld
2001-07-27 14:23 ` Hans Reiser
2001-07-27 14:21 ` Alan Cox
2001-07-28 14:18 ` Matthew Gardiner
2001-07-28 16:25 ` Alan Cox
2001-07-29 10:15 ` Matthew Gardiner
2001-07-29 11:10 ` Chris Wedgwood
2001-07-29 14:28 ` Luigi Genoni
2001-07-29 11:16 ` Christoph Hellwig
2001-07-27 15:06 ` Alan Cox
2001-07-27 15:26 ` Joshua Schmidlkofer
2001-07-27 15:46 ` Hans Reiser
2001-07-27 17:46 ` Christoph Rohland
2001-07-27 18:02 ` Hans Reiser
2001-07-27 18:10 ` Dustin Byford
2001-07-27 19:20 ` Hans Reiser
2001-07-28 16:10 ` Henning P. Schmiedehausen
2001-07-27 15:31 ` Hans Reiser
2001-07-27 16:25 ` Kip Macy
2001-07-27 17:29 ` Ville Herva
2001-07-27 17:40 ` Alan Cox
2001-07-27 17:43 ` Ville Herva
2001-07-27 20:46 ` Lehmann
2001-07-27 21:13 ` Hans Reiser
2001-07-27 15:51 ` Alan Cox
2001-07-27 16:41 ` Hans Reiser
2001-07-27 16:55 ` Alan Cox
2001-07-27 21:24 ` Alan Cox
2001-07-27 21:47 ` Hans Reiser
2001-07-27 22:10 ` Alan Cox
2001-07-28 7:36 ` Hans Reiser
2001-07-28 14:08 ` Chris Mason
2001-07-27 15:13 Cress, Andrew R
2001-07-30 15:24 Chris Mason
2001-07-30 15:47 ` Andrew Morton
2001-07-30 16:04 ` Chris Mason
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