From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 422B66B0026 for ; Thu, 28 Apr 2011 11:47:40 -0400 (EDT) Date: Thu, 28 Apr 2011 10:47:36 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH] percpu: preemptless __per_cpu_counter_add In-Reply-To: <20110428154012.GG16552@htj.dyndns.org> Message-ID: References: <20110428142331.GA16552@htj.dyndns.org> <20110428144446.GC16552@htj.dyndns.org> <20110428145657.GD16552@htj.dyndns.org> <20110428151203.GE16552@htj.dyndns.org> <20110428153101.GF16552@htj.dyndns.org> <20110428154012.GG16552@htj.dyndns.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Shaohua Li , Eric Dumazet , "akpm@linux-foundation.org" , "linux-mm@kvack.org" On Thu, 28 Apr 2011, Tejun Heo wrote: > On Thu, Apr 28, 2011 at 05:31:01PM +0200, Tejun Heo wrote: > > > The hugely expensive _sum() is IMHO pretty useless given the above. It is > > > a function that is called with the *hope* of getting a more accurate > > > result. > ... > > Christoph, I'm sorry but I really can't explain it any better and am > > out of this thread. If you still wanna proceed, you'll need to route > > the patches yourself. Please keep me cc'd. > > Oh, another way to proceed would be, if _sum() is as useless as you > suggested above, remove _sum() first and see how that goes. If that > flies, there will be no reason to argue over anything, right? There is no point of arguing anymore since you do not accept that the percpu counters do not have atomic_t consistency properties. The relaxing of the consistency requirements in order to increase performance was the intend when these schemes were created. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org