From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f48.google.com (mail-ee0-f48.google.com [74.125.83.48]) by kanga.kvack.org (Postfix) with ESMTP id C78216B0035 for ; Wed, 11 Dec 2013 03:37:48 -0500 (EST) Received: by mail-ee0-f48.google.com with SMTP id e49so2675596eek.21 for ; Wed, 11 Dec 2013 00:37:48 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTP id e48si17973762eeh.155.2013.12.11.00.37.47 for ; Wed, 11 Dec 2013 00:37:47 -0800 (PST) Date: Wed, 11 Dec 2013 08:37:45 +0000 From: Mel Gorman Subject: Re: [PATCH 17/18] sched: Add tracepoints related to NUMA task migration Message-ID: <20131211083744.GP11295@suse.de> References: <1386690695-27380-1-git-send-email-mgorman@suse.de> <1386690695-27380-18-git-send-email-mgorman@suse.de> <20131210142211.099fe782c361707ab3c04742@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20131210142211.099fe782c361707ab3c04742@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Alex Thorlton , Rik van Riel , Linux-MM , LKML On Tue, Dec 10, 2013 at 02:22:11PM -0800, Andrew Morton wrote: > On Tue, 10 Dec 2013 15:51:35 +0000 Mel Gorman wrote: > > > This patch adds three tracepoints > > o trace_sched_move_numa when a task is moved to a node > > o trace_sched_swap_numa when a task is swapped with another task > > o trace_sched_stick_numa when a numa-related migration fails > > > > The tracepoints allow the NUMA scheduler activity to be monitored and the > > following high-level metrics can be calculated > > > > o NUMA migrated stuck nr trace_sched_stick_numa > > o NUMA migrated idle nr trace_sched_move_numa > > o NUMA migrated swapped nr trace_sched_swap_numa > > o NUMA local swapped trace_sched_swap_numa src_nid == dst_nid (should never happen) > > o NUMA remote swapped trace_sched_swap_numa src_nid != dst_nid (should == NUMA migrated swapped) > > o NUMA group swapped trace_sched_swap_numa src_ngid == dst_ngid > > Maybe a small number of these are acceptable > > but a high number would be a major surprise. > > It would be even worse if bounces are frequent. > > o NUMA avg task migs. Average number of migrations for tasks > > o NUMA stddev task mig Self-explanatory > > o NUMA max task migs. Maximum number of migrations for a single task > > > > In general the intent of the tracepoints is to help diagnose problems > > where automatic NUMA balancing appears to be doing an excessive amount of > > useless work. > > > > ... > > > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -1272,11 +1272,13 @@ static int task_numa_migrate(struct task_struct *p) > > p->numa_scan_period = task_scan_min(p); > > > > if (env.best_task == NULL) { > > - int ret = migrate_task_to(p, env.best_cpu); > > + if ((ret = migrate_task_to(p, env.best_cpu)) != 0) > > + trace_sched_stick_numa(p, env.src_cpu, env.best_cpu); > > return ret; > > } > > > > - ret = migrate_swap(p, env.best_task); > > + if ((ret = migrate_swap(p, env.best_task)) != 0); > > I'll zap that semicolon... > Thanks -- Mel Gorman SUSE Labs -- 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