From: Dave Chinner <david@fromorbit.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>,
Peter Zijlstra <peterz@infradead.org>,
Eric Paris <eparis@redhat.com>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, hch@infradead.org,
zohar@us.ibm.com, warthog9@kernel.org, jmorris@namei.org,
kyle@mcmartin.ca, hpa@zytor.com, akpm@linux-foundation.org,
mingo@elte.hu, viro@zeniv.linux.org.uk
Subject: Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for inode information cache
Date: Thu, 21 Oct 2010 13:17:51 +1100 [thread overview]
Message-ID: <20101021021751.GH12506@dastard> (raw)
In-Reply-To: <AANLkTi=HAQEqqswmueJHoc5ez3Bq1_3X2xZkO9sg8gzZ@mail.gmail.com>
On Wed, Oct 20, 2010 at 05:58:19PM -0700, Linus Torvalds wrote:
> On Wed, Oct 20, 2010 at 3:47 PM, Trond Myklebust
> <Trond.Myklebust@netapp.com> wrote:
> >
> > That is a really interesting alternative to traditional locking. Could
> > we perhaps document it in Documentation/rbtree.txt?
>
> Well, I'd actually suggest avoiding it unless you feel that you
> _really_ need it. So I wouldn't want to really suggest it as a generic
> locking model - you had better have looked at pretty much all other
> alternatives first. And if that seqlock starts failing a lot under
> load, it ends up being _more_ expensive than just taking the lock in
> the first place.
Thanks for pointing out that caveat. I think that the XFS buffer
cache case won't have that problem - I'm seeing better than a 100:1
tree lookup (>1M/s) to modification rate (<10k inserts/s) under
workloads that are stressing the cache on an 8-way VM...
Still, as the only method I've heard of that allows RCU lookup on
rbtrees, perhaps it is still worth documenting along with all the
caveats of when not to use this.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2010-10-21 2:19 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-19 22:58 [PATCH 1/6] IMA: move read/write counters into struct inode Eric Paris
2010-10-19 22:58 ` [PATCH 2/6] IMA: drop the inode opencount since it isn't needed for operation Eric Paris
2010-10-19 22:58 ` [PATCH 3/6] IMA: use unsigned int instead of long for counters Eric Paris
2010-10-19 22:58 ` [PATCH 4/6] IMA: only allocate iint when needed Eric Paris
2010-10-20 3:53 ` Al Viro
2010-10-19 22:58 ` [PATCH 5/6] IMA: use rbtree instead of radix tree for inode information cache Eric Paris
2010-10-19 23:17 ` Dave Chinner
2010-10-20 11:31 ` Peter Zijlstra
2010-10-20 22:05 ` Dave Chinner
2010-10-20 22:22 ` Linus Torvalds
2010-10-20 22:47 ` Trond Myklebust
2010-10-21 0:58 ` Linus Torvalds
2010-10-21 2:17 ` Dave Chinner [this message]
2010-10-19 22:58 ` [PATCH 6/6] IMA: use i_writecount rather than a private counter Eric Paris
2010-10-20 0:25 ` [PATCH 1/6] IMA: move read/write counters into struct inode Linus Torvalds
2010-10-23 3:01 ` Eric Paris
2010-10-24 6:52 ` Mimi Zohar
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=20101021021751.GH12506@dastard \
--to=david@fromorbit.com \
--cc=Trond.Myklebust@netapp.com \
--cc=akpm@linux-foundation.org \
--cc=eparis@redhat.com \
--cc=hch@infradead.org \
--cc=hpa@zytor.com \
--cc=jmorris@namei.org \
--cc=kyle@mcmartin.ca \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=peterz@infradead.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
--cc=warthog9@kernel.org \
--cc=zohar@us.ibm.com \
/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).