From: Christoph Lameter <cl@linux-foundation.org>
To: paulmck@linux.vnet.ibm.com
Cc: Pekka Enberg <penberg@cs.helsinki.fi>,
Ingo Molnar <mingo@elte.hu>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Andi Kleen <andi@firstfloor.org>,
"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
Suresh Siddha <suresh.b.siddha@intel.com>,
Jens Axboe <jens.axboe@oracle.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] smp_call_function: use rwlocks on queues rather than rcu
Date: Fri, 22 Aug 2008 12:14:37 -0500 [thread overview]
Message-ID: <48AEF3FD.70906@linux-foundation.org> (raw)
In-Reply-To: <20080822151156.GA6744@linux.vnet.ibm.com>
Paul E. McKenney wrote:
>> RCU is problematic because it lets cachelines get cold. A hot cacheline that
>> is used frequently read and written to by the same cpu is very good thing for
>> performace.
>
> So on your these large boxes, read-only cachelines are preferentially
> ejected from the cache, so that one should write to per-CPU data
> occasionally to keep it resident? Or is the issue the long RCU grace
> periods which allow the structure being freed to age out of all relevant
> caches? (My guess would be the second.)
The issue are the RCU grace period that are generally long enough to make the
cacheline fall out of all caches.
next prev parent reply other threads:[~2008-08-22 17:21 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-22 0:29 [PATCH 2/2] smp_call_function: use rwlocks on queues rather than rcu Jeremy Fitzhardinge
2008-08-22 1:53 ` Nick Piggin
2008-08-22 6:28 ` Ingo Molnar
2008-08-22 7:06 ` Pekka Enberg
2008-08-22 7:12 ` Ingo Molnar
2008-08-22 9:12 ` Nick Piggin
2008-08-22 14:01 ` Christoph Lameter
2008-08-22 15:11 ` Paul E. McKenney
2008-08-22 17:14 ` Christoph Lameter [this message]
2008-08-22 18:29 ` Paul E. McKenney
2008-08-22 18:33 ` Andi Kleen
2008-08-22 18:35 ` Jeremy Fitzhardinge
2008-08-23 7:34 ` Andi Kleen
2008-08-24 4:55 ` Jeremy Fitzhardinge
2008-08-24 9:01 ` Andi Kleen
2008-08-22 22:40 ` Paul E. McKenney
2008-08-22 18:36 ` Christoph Lameter
2008-08-22 19:52 ` Paul E. McKenney
2008-08-22 20:03 ` Christoph Lameter
2008-08-22 20:53 ` Paul E. McKenney
2008-08-25 10:31 ` Peter Zijlstra
2008-08-25 15:12 ` Paul E. McKenney
2008-08-25 15:22 ` Peter Zijlstra
2008-08-25 15:46 ` Christoph Lameter
2008-08-25 15:51 ` Peter Zijlstra
2008-08-26 13:43 ` Paul E. McKenney
2008-08-26 14:07 ` Peter Zijlstra
2008-08-27 15:16 ` Paul E. McKenney
2008-08-25 20:04 ` Paul E. McKenney
2008-08-26 5:13 ` Nick Piggin
2008-08-26 13:40 ` [PATCH 2/2] smp_call_function: use rwlocks on queues rather?than rcu Paul E. McKenney
2008-08-25 15:44 ` [PATCH 2/2] smp_call_function: use rwlocks on queues rather than rcu Christoph Lameter
2008-08-25 20:05 ` Paul E. McKenney
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