From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756665Ab3GDMsh (ORCPT ); Thu, 4 Jul 2013 08:48:37 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:54598 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751468Ab3GDMsd (ORCPT ); Thu, 4 Jul 2013 08:48:33 -0400 Date: Thu, 4 Jul 2013 18:18:23 +0530 From: Srikar Dronamraju To: Mel Gorman Cc: Peter Zijlstra , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML Subject: Re: [PATCH 11/13] sched: Check current->mm before allocating NUMA faults Message-ID: <20130704124823.GB29916@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <1372861300-9973-1-git-send-email-mgorman@suse.de> <1372861300-9973-12-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1372861300-9973-12-git-send-email-mgorman@suse.de> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13070412-3620-0000-0000-00000365075F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mel Gorman [2013-07-03 15:21:38]: > task_numa_placement checks current->mm but after buffers for faults > have already been uselessly allocated. Move the check earlier. > > [peterz@infradead.org: Identified the problem] > Signed-off-by: Mel Gorman > --- > kernel/sched/fair.c | 22 ++++++++++++++-------- > 1 file changed, 14 insertions(+), 8 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 336074f..3c796b0 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -870,8 +870,6 @@ static void task_numa_placement(struct task_struct *p) > int seq, nid, max_nid = 0; > unsigned long max_faults = 0; > > - if (!p->mm) /* for example, ksmd faulting in a user's mm */ > - return; > seq = ACCESS_ONCE(p->mm->numa_scan_seq); > if (p->numa_scan_seq == seq) > return; > @@ -945,6 +943,12 @@ void task_numa_fault(int last_nid, int node, int pages, bool migrated) > if (!sched_feat_numa(NUMA)) > return; > > + /* for example, ksmd faulting in a user's mm */ > + if (!p->mm) { > + p->numa_scan_period = sysctl_numa_balancing_scan_period_max; Naive question: Why are we resetting the scan_period? > + return; > + } > + > /* Allocate buffer to track faults on a per-node basis */ > if (unlikely(!p->numa_faults)) { > int size = sizeof(*p->numa_faults) * 2 * nr_node_ids; > @@ -1072,16 +1076,18 @@ void task_numa_work(struct callback_head *work) > end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); > end = min(end, vma->vm_end); > nr_pte_updates += change_prot_numa(vma, start, end); > - pages -= (end - start) >> PAGE_SHIFT; > - > - start = end; > > /* > * Scan sysctl_numa_balancing_scan_size but ensure that > - * least one PTE is updated so that unused virtual > - * address space is quickly skipped > + * at least one PTE is updated so that unused virtual > + * address space is quickly skipped. > */ > - if (pages <= 0 && nr_pte_updates) > + if (nr_pte_updates) > + pages -= (end - start) >> PAGE_SHIFT; > + > + start = end; > + > + if (pages <= 0) > goto out; > } while (end != vma->vm_end); > } > -- > 1.8.1.4 > -- Thanks and Regards Srikar Dronamraju