From: Ingo Molnar <mingo@elte.hu>
To: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Lameter <clameter@sgi.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Linus Torvalds <torvalds@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: Major regression on hackbench with SLUB (more numbers)
Date: Sat, 22 Dec 2007 11:03:26 +0100 [thread overview]
Message-ID: <20071222100326.GF26157@elte.hu> (raw)
In-Reply-To: <p731w9ffu8c.fsf@bingen.suse.de>
* Andi Kleen <andi@firstfloor.org> wrote:
> Ingo Molnar <mingo@elte.hu> writes:
>
> > Christoph, /proc/slabinfo is an _ABI_. You HAVE to provide it.
> > slabtop relies on it, people use it every day to monitor memory
> > consumption.
>
> It's definitely not a stable ABI. slabtop tends to exit without any
> error message on any slabinfo version number increase and I've seen
> that happen several times in not so old kernels.
so because we sucked in the past we can continue to suck? ;)
Why are we still arguing about this? We kernel developers are foxes
amongst the hens and if a compatibility issue comes up we have to act
_doubly_ conservatively.
You think it's reasonable to not offer /proc/slabinfo? You can fairly
assume that a user considers it absolutely unreasonable. If other kernel
developers tell you: "no, it's fine", then it's as if other foxes told
you "no, it's fine to eat that hen, we do it all the time too!" ;-)
> Requiring just another slabtop update isn't really a big deal.
certainly. But consider this from the user's perspective who tries one
of our devel kernels. He suspects a memory leak. Runs slabtop and
gets:
$ slabtop
fopen /proc/slabinfo: No such file or directory
and would fairly conclude: "ok, this new Linux kernel looks quite
apparently unfinished, i'm outta here".
We do this way too frequently and many silly details like this _do_
mount up.
> Also it's not that it's a critical functionality like udev.
Sure, we can argue about details that not all fields in /proc/slabinfo
are relevant, and that slabtop should be a bit more careful, etc., but
we've got what we've got because _we_ built the current code, so we
might as well accept the consequences it brings. The most of the basic
output of slabtop:
Active / Total Objects (% used) : 648754 / 747076 (86.8%)
Active / Total Slabs (% used) : 39394 / 39394 (100.0%)
Active / Total Caches (% used) : 103 / 143 (72.0%)
Active / Total Size (% used) : 138884.36K / 151075.96K (91.9%)
Minimum / Average / Maximum Object : 0.01K / 0.20K / 128.00K
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
261928 239808 91% 0.13K 9032 29 36128K dentry_cache
222048 174144 78% 0.05K 3084 72 12336K buffer_head
187232 178929 95% 0.48K 23404 8 93616K ext3_inode_cache
24416 17908 73% 0.27K 1744 14 6976K radix_tree_node
could be offered on SLUB too.
'top' isnt critical functionality either like udev, and the ABI does not
only cover 'critical' functionality. A utility suddenly not working
gives Linux a pretty amateurish feeling. Should we tell users/admins:
"Hehe, gotcha! Didnt you know /proc/slabinfo was not an ABI? Poor sob.
If you want your stuff to continue working, use Windows next time around
or what. Sheesh, what do these people want!' ;-)
the rule is very simple: unless you have really, really, really, REALLY
good reasons, just dont break stuff.
Ingo
next prev parent reply other threads:[~2007-12-22 10:04 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-07 17:50 Major regression on hackbench with SLUB Steven Rostedt
2007-12-07 17:55 ` Ingo Molnar
2007-12-07 17:59 ` Linus Torvalds
2007-12-07 18:36 ` Linus Torvalds
2007-12-07 18:58 ` Steven Rostedt
2007-12-08 22:16 ` Steven Rostedt
2007-12-10 7:38 ` Björn Steinbrink
2007-12-10 14:00 ` Steven Rostedt
2007-12-09 0:28 ` Steven Rostedt
2007-12-13 22:11 ` Christoph Lameter
2007-12-11 14:33 ` Major regression on hackbench with SLUB (more numbers) Ingo Molnar
2007-12-13 22:22 ` Christoph Lameter
2007-12-14 4:24 ` Christoph Lameter
2007-12-14 6:15 ` Steven Rostedt
2007-12-21 12:09 ` Ingo Molnar
2007-12-21 12:26 ` Ingo Molnar
2007-12-21 16:26 ` Christoph Lameter
2007-12-21 16:33 ` Ingo Molnar
2007-12-21 21:56 ` Christoph Lameter
2007-12-21 16:18 ` Christoph Lameter
2007-12-21 16:44 ` Linus Torvalds
2007-12-21 22:11 ` Christoph Lameter
2007-12-21 22:16 ` Peter Zijlstra
2007-12-21 22:17 ` Peter Zijlstra
2007-12-21 22:27 ` Christoph Lameter
2007-12-21 22:54 ` Ingo Molnar
2007-12-21 23:20 ` David Miller
2007-12-22 9:45 ` Ingo Molnar
2007-12-24 19:24 ` Christoph Lameter
2007-12-21 23:27 ` Andrew Morton
2007-12-21 23:51 ` Christoph Lameter
2007-12-22 0:28 ` Andi Kleen
2007-12-22 0:33 ` Chuck Ebbert
2007-12-22 2:19 ` Matt Mackall
2007-12-22 2:44 ` Andi Kleen
2007-12-22 10:03 ` Ingo Molnar [this message]
2007-12-22 12:37 ` Andi Kleen
2007-12-22 12:51 ` Pekka Enberg
2007-12-22 12:54 ` Andi Kleen
2007-12-22 13:27 ` Pekka Enberg
2007-12-22 13:01 ` Alexey Dobriyan
2007-12-22 18:01 ` Linus Torvalds
2007-12-22 19:09 ` Ingo Molnar
2007-12-22 19:29 ` Ingo Molnar
2007-12-22 22:52 ` Jason L Tibbitts III
2007-12-24 3:59 ` Alessandro Suardi
2007-12-22 19:25 ` Theodore Tso
2007-12-22 21:00 ` Linus Torvalds
2007-12-22 21:50 ` Al Viro
2007-12-22 23:29 ` Al Viro
2007-12-22 22:10 ` Willy Tarreau
2007-12-23 0:59 ` Steven Rostedt
2007-12-23 5:12 ` Willy Tarreau
2007-12-23 14:15 ` Andi Kleen
2007-12-24 3:45 ` Theodore Tso
2007-12-24 19:21 ` Christoph Lameter
2007-12-24 23:37 ` Theodore Tso
2007-12-25 3:34 ` Andi Kleen
2008-01-01 12:47 ` Theodore Tso
2008-01-01 15:19 ` Andi Kleen
2008-01-01 16:23 ` [patch] slub: provide /proc/slabinfo Ingo Molnar
2008-01-05 0:27 ` Arjan van de Ven
2008-01-05 0:49 ` Linus Torvalds
2007-12-26 21:31 ` Major regression on hackbench with SLUB (more numbers) Christoph Lameter
2007-12-26 22:16 ` Al Viro
2007-12-27 5:51 ` Christoph Lameter
2007-12-27 20:28 ` SLUB sysfs support Christoph Lameter
2007-12-27 22:59 ` Al Viro
2007-12-27 23:22 ` Christoph Lameter
2007-12-27 23:53 ` Christoph Lameter
2007-12-27 23:58 ` Al Viro
2007-12-28 0:02 ` Christoph Lameter
2007-12-28 0:45 ` Al Viro
2007-12-28 2:19 ` Christoph Lameter
2007-12-28 3:26 ` Al Viro
2008-01-02 20:25 ` Christoph Lameter
2007-12-27 23:54 ` Al Viro
2007-12-28 9:00 ` Major regression on hackbench with SLUB (more numbers) Ingo Molnar
2007-12-28 14:52 ` Steven Rostedt
2007-12-22 19:46 ` slabtop replacement was " Andi Kleen
2007-12-22 23:28 ` Karol Swietlicki
2007-12-29 18:08 ` Karol Swietlicki
2007-12-21 22:49 ` Linus Torvalds
2007-12-21 17:44 ` Pekka Enberg
2007-12-21 22:22 ` Christoph Lameter
2007-12-21 22:37 ` Christoph Lameter
2007-12-21 22:51 ` Linus Torvalds
2007-12-21 23:17 ` Ingo Molnar
2007-12-21 23:40 ` Pekka Enberg
2007-12-21 23:54 ` Christoph Lameter
2007-12-22 0:02 ` Chuck Ebbert
2007-12-21 22:52 ` Steven Rostedt
2007-12-21 22:56 ` Ingo Molnar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20071222100326.GF26157@elte.hu \
--to=mingo@elte.hu \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=andi@firstfloor.org \
--cc=clameter@sgi.com \
--cc=hch@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rjw@sisk.pl \
--cc=rostedt@goodmis.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).