From: Rik van Riel <riel@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Waiman Long <Waiman.Long@hp.com>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
Emmanuel Benisty <benisty.e@gmail.com>,
"Vinod, Chegu" <chegu_vinod@hp.com>,
"Low, Jason" <jason.low2@hp.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
aquini@redhat.com, Michel Lespinasse <walken@google.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: [PATCH v2 0/4] ipc: reduce ipc lock contention
Date: Tue, 05 Mar 2013 15:53:58 -0500 [thread overview]
Message-ID: <51365B66.5010905@redhat.com> (raw)
In-Reply-To: <CA+55aFwYOUyG_DQUqVPrQNi_a=AUwS53U-Yi6jbvJTGRxQ_aEQ@mail.gmail.com>
On 03/05/2013 03:52 PM, Linus Torvalds wrote:
> On Tue, Mar 5, 2013 at 11:42 AM, Waiman Long <Waiman.Long@hp.com> wrote:
>>
>> The recommended kernel.sem value from Oracle is "250 32000 100 128". I have
>> tried to reduce the maximum semaphores per array (1st value) while
>> increasing the max number of arrays. That tends to reduce the ipc_lock
>> contention in kernel, but it is against Oracle's recommendation.
>
> Ok, the Oracle recommendations seem to be assuming that we'd be
> scaling the semaphore locking sanely, which we don't. Since we share
> one single lock for all semaphores in the whole array, Oracle's
> recommendation does the wrong thing for our ipc_lock contention.
> David's patch should make it much easier to do the locking more
> fine-grained, and it sounds like Rik is actively working on that,
Indeed. Though how well my patches will work with Oracle will
depend a lot on what kind of semctl syscalls they are doing.
Does Oracle typically do one semop per semctl syscall, or does
it pass in a whole bunch at once?
--
All rights reversed
next prev parent reply other threads:[~2013-03-05 20:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-05 9:35 [PATCH v2 0/4] ipc: reduce ipc lock contention Davidlohr Bueso
2013-03-05 15:40 ` Linus Torvalds
2013-03-06 7:13 ` Davidlohr Bueso
2013-03-06 16:01 ` Linus Torvalds
2013-03-05 17:10 ` Rik van Riel
2013-03-05 19:42 ` Waiman Long
2013-03-05 20:52 ` Linus Torvalds
2013-03-05 20:53 ` Rik van Riel [this message]
2013-03-06 3:46 ` Waiman Long
2013-03-06 3:53 ` Rik van Riel
2013-03-06 7:14 ` Davidlohr Bueso
2013-03-07 8:45 ` Peter Zijlstra
2013-03-07 12:55 ` Chris Mason
2013-03-07 15:54 ` Dave Kleikamp
2013-03-07 16:42 ` Chris Mason
2013-03-06 22:13 ` [PATCH v2 5/4] ipc: replace ipc_perm.lock with an rwlock Rik van Riel
2013-03-06 22:14 ` [PATCH v2 6/4] ipc: open code and rename sem_lock Rik van Riel
2013-03-06 22:15 ` [PATCH v2 7/4] ipc: fine grained locking for semtimedop Rik van Riel
2013-03-06 22:57 ` Linus Torvalds
2013-03-06 23:09 ` Rik van Riel
2013-03-07 1:36 ` Davidlohr Bueso
2013-03-07 20:55 ` Rik van Riel
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