From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758144Ab1DMTH4 (ORCPT ); Wed, 13 Apr 2011 15:07:56 -0400 Received: from mail-vx0-f174.google.com ([209.85.220.174]:37351 "EHLO mail-vx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757105Ab1DMTHy (ORCPT ); Wed, 13 Apr 2011 15:07:54 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=L2jAlQdMvXiUMzWMSQZMU02PCvly4QLCXh5XbXW+d96SLKmt3dfwEJD1707Ig6BPCA hzXZN/61gErYT96i/zWXjvR+3wu6M5O5FFA8FeWVa3tP5hAFaqzydmUB0fIr52FQih9D DWmO5J8bq9x4Sr3WhhraxQ7aFr6kvpNWPd404= Date: Thu, 14 Apr 2011 04:07:47 +0900 From: Tejun Heo To: shaohua.li@intel.com Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, cl@linux.com, eric.dumazet@gmail.com Subject: Re: [patch v2 4/4] percpu_counter: use atomic64 for counter Message-ID: <20110413190747.GE3987@mtj.dyndns.org> References: <20110413075715.090406229@sli10-conroe.sh.intel.com> <20110413080517.901701497@sli10-conroe.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110413080517.901701497@sli10-conroe.sh.intel.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 13, 2011 at 03:57:19PM +0800, shaohua.li@intel.com wrote: > This can improve some workloads with percpu_counter->lock heavily contented. > For example, vm_committed_as sometimes causes the contention. We should tune > the batch count, but if we can make percpu_counter better, why not? In a 24 > CPUs system, 24 processes run stress mmap()/mmunmap(), the atomic method > gives 50x faster. Christoph already raised the issue but I'd also love to know a bit more detail on the test than "50x faster". Thanks. -- tejun