From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752910AbaCGSQu (ORCPT ); Fri, 7 Mar 2014 13:16:50 -0500 Received: from qmta02.emeryville.ca.mail.comcast.net ([76.96.30.24]:42841 "EHLO qmta02.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751545AbaCGSQs (ORCPT ); Fri, 7 Mar 2014 13:16:48 -0500 Date: Fri, 7 Mar 2014 12:16:45 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@nuc To: Mike Travis cc: Andrew Morton , Tejun Heo , akpm@linuxfoundation.org, rostedt@goodmis.org, linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Hedi Berriche , Dimitri Sivanich Subject: Re: [PATCH 31/48] uv: Replace __get_cpu_var In-Reply-To: <5317E33F.5000206@sgi.com> Message-ID: References: <20140214201841.826179349@linux.com> <20140214201907.228035121@linux.com> <20140304150217.ac9d364008a3c95cb2a79b34@linux-foundation.org> <20140304200023.7b991909.akpm@linux-foundation.org> <5317E33F.5000206@sgi.com> 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 Wed, 5 Mar 2014, Mike Travis wrote: > I haven't had much chance yet to look over your proposed changes but > FYI, the counters are strictly feedback to insure that there are not > unhandled NMI events from the perf subsystem. The exact count is > irrelevant. IOW, counts in the double or triple digits is okay, > counts > 100,000 is definitely not okay (there are multiple millions > of perf events every 'perf top' refresh.) > > I'm not sure if this alters how you want to approach the changes. Gotta patch here that converts all the atomic per cpu counters to int but the local64_t definitions look very strange to me. I have never seen a local64_t definition that is global and used for a counters. That can only work if there is only one and exactly one processor that is modifying the count.