From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qa0-f46.google.com (mail-qa0-f46.google.com [209.85.216.46]) by kanga.kvack.org (Postfix) with ESMTP id B0C2A6B0035 for ; Mon, 20 Jan 2014 14:05:54 -0500 (EST) Received: by mail-qa0-f46.google.com with SMTP id ii20so5865955qab.33 for ; Mon, 20 Jan 2014 11:05:54 -0800 (PST) Received: from cdptpa-oedge-vip.email.rr.com (cdptpa-outbound-snat.email.rr.com. [107.14.166.225]) by mx.google.com with ESMTP id f91si1290172qge.48.2014.01.20.11.05.53 for ; Mon, 20 Jan 2014 11:05:53 -0800 (PST) Date: Mon, 20 Jan 2014 14:05:51 -0500 From: Steven Rostedt Subject: Re: [PATCH 4/7] numa,sched: tracepoints for NUMA balancing active nodemask changes Message-ID: <20140120140551.3343ab2b@gandalf.local.home> In-Reply-To: <20140120165205.GJ31570@twins.programming.kicks-ass.net> References: <1389993129-28180-1-git-send-email-riel@redhat.com> <1389993129-28180-5-git-send-email-riel@redhat.com> <20140120165205.GJ31570@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: riel@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, chegu_vinod@hp.com, mgorman@suse.de, mingo@redhat.com On Mon, 20 Jan 2014 17:52:05 +0100 Peter Zijlstra wrote: > On Fri, Jan 17, 2014 at 04:12:06PM -0500, riel@redhat.com wrote: > > From: Rik van Riel > > > > +++ b/kernel/sched/fair.c > > @@ -1300,10 +1300,14 @@ static void update_numa_active_node_mask(struct task_struct *p) > > faults = numa_group->faults_from[task_faults_idx(nid, 0)] + > > numa_group->faults_from[task_faults_idx(nid, 1)]; > > if (!node_isset(nid, numa_group->active_nodes)) { > > - if (faults > max_faults * 4 / 10) > > + if (faults > max_faults * 4 / 10) { > > + trace_update_numa_active_nodes_mask(current->pid, numa_group->gid, nid, true, faults, max_faults); > > While I think the tracepoint hookery is smart enough to avoid evaluating > arguments when they're disabled, it might be best to simply pass: > current and numa_group and do the dereference in fast_assign(). It's really up to gcc to optimize it. But that said, it is more efficient to just past the pointer and do the dereferencing in the fast_assign(). At least it keeps any bad optimization in gcc from infecting the tracepoint caller. It also makes it easier to get other information if you want to later extend that tracepoint. Does this tracepoint always use current? If so, why bother passing it in? -- Steve -- 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/ . Don't email: email@kvack.org