From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: reminder, 2.6.18 window... Date: Fri, 26 May 2006 11:52:39 +0200 Message-ID: <200605261152.40101.ak@suse.de> References: <20060523.182217.59656237.davem@davemloft.net> <20060525032357.4990425f.billfink@mindspring.com> <200605250805.38241.bcook@bpointsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Bill Fink , Jeff Garzik , phil@ipom.com, davem@davemloft.net, netdev@vger.kernel.org Return-path: Received: from ns.suse.de ([195.135.220.2]:9696 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S1751325AbWEZJwo (ORCPT ); Fri, 26 May 2006 05:52:44 -0400 To: Brent Cook In-Reply-To: <200605250805.38241.bcook@bpointsys.com> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org > The current patch is fine if your hardware implements the required atomicity > itself. Near all do optionally, but it would make increasing the statistics a magnitude more expensive. Atomic operations don't come cheap on modern systems. And you would need to change the fast path increments to atomic for this. I suspect it could be done without atomics with some tricks (e.g. use a double set of counters and switch on clear and use RCU), but it would make the whole thing quite complex and still have more overhead in the fast path than the current code. -Andi