All of lore.kernel.org
 help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Hellwig <hch@lst.de>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH, RFC] xfs: remove i_iolock and use i_rwsem in the VFS inode instead
Date: Fri, 9 Sep 2016 10:44:50 +0200	[thread overview]
Message-ID: <20160909084450.GF10153@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160909083306.GA19964@lst.de>

On Fri, Sep 09, 2016 at 10:33:06AM +0200, Christoph Hellwig wrote:
> On Thu, Sep 08, 2016 at 07:45:36AM +1000, Dave Chinner wrote:
> > It's a semaphore, not a mutex. Semaphore locking is independent of
> > task context, the lock follows the object it protects, not the task
> > that took the lock. i.e. Lockdep is wrong to assume the "owner" of a
> > rw_sem will not change between lock and unlock.
> 
> That's not the case - rw_semaphores had strict owner semanics for a
> long time (although I wish we could get rid of that for a different
> reason..).

Do tell; note however that due to the strict write owner, we can do
things like the optimistic spinning which improved writer->writer
performance significantly.

Also note that !owner locks create problems for RT.

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

  reply	other threads:[~2016-09-09  8:44 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-11 17:10 [PATCH, RFC] xfs: remove i_iolock and use i_rwsem in the VFS inode instead Christoph Hellwig
2016-08-11 21:54 ` Peter Zijlstra
2016-08-18 17:37   ` Christoph Hellwig
2016-08-19 13:27     ` Peter Zijlstra
2016-08-20  6:37       ` Christoph Hellwig
2016-08-22  8:34         ` Peter Zijlstra
2016-09-05 15:12           ` Christoph Hellwig
2016-09-07  7:43             ` Peter Zijlstra
2016-09-08  6:06               ` Ingo Molnar
2016-08-11 23:43 ` Dave Chinner
2016-08-12  2:50   ` Christoph Hellwig
2016-08-12  9:58     ` Dave Chinner
2016-09-05 15:15       ` Christoph Hellwig
2016-09-07 21:45         ` Dave Chinner
2016-09-08  6:54           ` Peter Zijlstra
2016-09-09  1:06             ` Dave Chinner
2016-09-09  8:21               ` Peter Zijlstra
2016-09-09  8:34                 ` Christoph Hellwig
2016-09-11  0:17                 ` Dave Chinner
2016-09-13 19:42                   ` Peter Zijlstra
2016-09-09  8:33           ` Christoph Hellwig
2016-09-09  8:44             ` Peter Zijlstra [this message]
2016-09-09  9:05               ` Christoph Hellwig
2016-09-09  9:51                 ` Peter Zijlstra
2016-09-10 16:20                   ` Christoph Hellwig

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=20160909084450.GF10153@twins.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=hch@lst.de \
    --cc=xfs@oss.sgi.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.