From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 96FF06B016A for ; Thu, 25 Aug 2011 11:11:54 -0400 (EDT) Date: Thu, 25 Aug 2011 10:11:50 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH] memcg: remove unneeded preempt_disable In-Reply-To: <1314284272.27911.32.camel@twins> Message-ID: References: <1313650253-21794-1-git-send-email-gthelen@google.com> <20110818144025.8e122a67.akpm@linux-foundation.org> <1314284272.27911.32.camel@twins> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Andrew Morton , Greg Thelen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, KAMEZAWA Hiroyuki , Balbir Singh , Daisuke Nishimura , linux-arch@vger.kernel.org On Thu, 25 Aug 2011, Peter Zijlstra wrote: > On Thu, 2011-08-18 at 14:40 -0700, Andrew Morton wrote: > > > > I think I'll apply it, as the call frequency is low (correct?) and the > > problem will correct itself as other architectures implement their > > atomic this_cpu_foo() operations. > > Which leads me to wonder, can anything but x86 implement that this_cpu_* > muck? I doubt any of the risk chips can actually do all this. > Maybe Itanic, but then that seems to be dying fast. The cpu needs to have an RMW instruction that does something to a variable relative to a register that points to the per cpu base. Thats generally possible. The problem is how expensive the RMW is going to be. -- 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