From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932373AbbCXSrL (ORCPT ); Tue, 24 Mar 2015 14:47:11 -0400 Received: from resqmta-ch2-04v.sys.comcast.net ([69.252.207.36]:40074 "EHLO resqmta-ch2-04v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752318AbbCXSrI (ORCPT ); Tue, 24 Mar 2015 14:47:08 -0400 Date: Tue, 24 Mar 2015 13:47:06 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Steven Rostedt cc: Linus Torvalds , LKML , Ingo Molnar , Andrew Morton , stable , Uwe Kleine-Koenig Subject: Re: [GIT PULL] ring-buffer: Replace this_cpu_*() with __this_cpu_*() In-Reply-To: <20150323134839.29dfdd08@gandalf.local.home> Message-ID: References: <20150319180216.62c9fa4a@gandalf.local.home> <20150323134839.29dfdd08@gandalf.local.home> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 23 Mar 2015, Steven Rostedt wrote: > Any comment on this? Yes we could do this but I am traveling a bit right now. Sorry not that responsive. It will not be strictly correct since a fetch or write could occur from a different cpu and thereby kick out a cacheline. But that is minor I think. The main issue is that this makes this_cpu_read/write different from other this_cpu operations which guarantee that these are "per cpu atomic" in the sense that they are either completely executed or not. But that is mostly important for this_cpu_ ops that are RMV operations like this_cpu_inc().