From mboxrd@z Thu Jan 1 00:00:00 1970 From: Evgeniy Polyakov Subject: Re: [PATCH 3/3] Convert the UDP hash lock to RCU Date: Tue, 7 Oct 2008 18:29:02 +0400 Message-ID: <20081007142902.GA26302@2ka.mipt.ru> References: <20081006185026.GA10383@minyard.local> <48EA8197.6080502@cosmosbay.com> <20081006.144002.56418911.davem@davemloft.net> <48EA9A59.1090306@acm.org> <20081007083750.GB17079@2ka.mipt.ru> <48EB6F2D.100@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Corey Minyard , David Miller , dada1@cosmosbay.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, shemminger@vyatta.com, paulmck@linux.vnet.ibm.com To: Christoph Lameter Return-path: Received: from relay.2ka.mipt.ru ([194.85.80.65]:57631 "EHLO 2ka.mipt.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753638AbYJGOpT (ORCPT ); Tue, 7 Oct 2008 10:45:19 -0400 Content-Disposition: inline In-Reply-To: <48EB6F2D.100@linux-foundation.org> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Oct 07, 2008 at 09:16:13AM -0500, Christoph Lameter (cl@linux-foundation.org) wrote: > > I tested skb destruction via RCU path, and got 2.5 times worse numbers > > with small-packets-bulk-transfer workload. > > Was this with regular RCU freeing? This will cool down the cacheline before > frees. You need SLAB_DESTROY_BY_RCU to keep the objects cache hot. I believe there were no SLAB_DESTROY_BY_RCU 2 yars ago :) It was pure call_rcu(&skb->rcu, real_skb_freeing), where real_skb_freeing() just did usual kfree(). -- Evgeniy Polyakov