From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f42.google.com (mail-pb0-f42.google.com [209.85.160.42]) by kanga.kvack.org (Postfix) with ESMTP id C57756B0035 for ; Tue, 10 Dec 2013 17:22:14 -0500 (EST) Received: by mail-pb0-f42.google.com with SMTP id uo5so8678314pbc.1 for ; Tue, 10 Dec 2013 14:22:14 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id sa6si11634755pbb.23.2013.12.10.14.22.12 for ; Tue, 10 Dec 2013 14:22:13 -0800 (PST) Date: Tue, 10 Dec 2013 14:22:11 -0800 From: Andrew Morton Subject: Re: [PATCH 17/18] sched: Add tracepoints related to NUMA task migration Message-Id: <20131210142211.099fe782c361707ab3c04742@linux-foundation.org> In-Reply-To: <1386690695-27380-18-git-send-email-mgorman@suse.de> References: <1386690695-27380-1-git-send-email-mgorman@suse.de> <1386690695-27380-18-git-send-email-mgorman@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Alex Thorlton , Rik van Riel , Linux-MM , LKML 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... > + trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); > put_task_struct(env.best_task); > return ret; > } -- 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