From: Mike Galbraith <bitbucket@online.de>
To: Rik van Riel <riel@redhat.com>
Cc: Michel Lespinasse <walken@google.com>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Vinod, Chegu" <chegu_vinod@hp.com>,
"Low, Jason" <jason.low2@hp.com>,
linux-tip-commits@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
aquini@redhat.com, Ingo Molnar <mingo@kernel.org>,
Larry Woodman <lwoodman@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC PATCH 1/2] ipc: introduce obtaining a lockless ipc object
Date: Sun, 03 Mar 2013 06:53:10 +0100 [thread overview]
Message-ID: <1362289990.4481.36.camel@marge.simpson.net> (raw)
In-Reply-To: <5132B2FB.4020004@redhat.com>
On Sat, 2013-03-02 at 21:18 -0500, Rik van Riel wrote:
> On 03/01/2013 11:32 PM, Michel Lespinasse wrote:
>
> > I think it may be nicer to take the rcu read lock at the call site
> > rather than in ipc_obtain_object(), to make the rcu read lock/unlock
> > sites pair up more nicely. Either that or make an inline
> > ipc_release_object function that pairs up with ipc_obtain_object() and
> > just does an rcu_read_unlock().
>
> I started on a patch series to untangle the IPC locking, so
> it will be a little more readable, and easier to maintain.
>
> It is a slower approach than Davidlohr's, as in, it will take
> a little longer to put a patch series together, but I hope it
> will be easier to debug...
>
> I hope to post a first iteration of the series by the middle
> of next week.
Goody, I'll be watching out for it. I have a big box rt user who uses
semaphores in their very tight constraint application. While they're
using them carefully, I saw a trace where contention cost vs jitter
budget was a bit too high for comfort, and semctl/semop collision.
-Mike
next prev parent reply other threads:[~2013-03-03 5:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-02 0:16 [RFC PATCH 1/2] ipc: introduce obtaining a lockless ipc object Davidlohr Bueso
2013-03-02 1:14 ` Linus Torvalds
2013-03-02 4:32 ` Michel Lespinasse
2013-03-03 2:18 ` Rik van Riel
2013-03-03 5:53 ` Mike Galbraith [this message]
2013-03-02 21:24 ` Linus Torvalds
2013-03-03 5:32 ` Davidlohr Bueso
2013-03-03 6:08 ` Linus Torvalds
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