From: Peter Zijlstra <peterz@infradead.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 05/16] sched: Select a preferred node with the most numa hinting faults
Date: Thu, 11 Jul 2013 13:23:59 +0200 [thread overview]
Message-ID: <20130711112359.GG25631@dyad.programming.kicks-ass.net> (raw)
In-Reply-To: <1373536020-2799-6-git-send-email-mgorman@suse.de>
On Thu, Jul 11, 2013 at 10:46:49AM +0100, Mel Gorman wrote:
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1593,6 +1593,7 @@ static void __sched_fork(struct task_struct *p)
> p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
> p->numa_migrate_seq = p->mm ? p->mm->numa_scan_seq - 1 : 0;
> p->numa_scan_period = sysctl_numa_balancing_scan_delay;
> + p->numa_preferred_nid = -1;
(1)
> p->numa_work.next = &p->numa_work;
> p->numa_faults = NULL;
> #endif /* CONFIG_NUMA_BALANCING */
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 904fd6f..c0bee41 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -793,7 +793,8 @@ unsigned int sysctl_numa_balancing_scan_delay = 1000;
>
> static void task_numa_placement(struct task_struct *p)
> {
> - int seq;
> + int seq, nid, max_nid = 0;
Should you not start with max_nid = -1?
> + unsigned long max_faults = 0;
>
> if (!p->mm) /* for example, ksmd faulting in a user's mm */
> return;
> @@ -802,7 +803,19 @@ static void task_numa_placement(struct task_struct *p)
> return;
> p->numa_scan_seq = seq;
>
> - /* FIXME: Scheduling placement policy hints go here */
> + /* Find the node with the highest number of faults */
> + for (nid = 0; nid < nr_node_ids; nid++) {
> + unsigned long faults = p->numa_faults[nid];
> + p->numa_faults[nid] >>= 1;
> + if (faults > max_faults) {
> + max_faults = faults;
> + max_nid = nid;
> + }
> + }
> +
It is rather unlikely; but suppose the entire ->numa_faults[] array is 0, you'd
somehow end up selecting max_nid := 0. Which seems inconsistent with \1.
> + /* Update the tasks preferred node if necessary */
> + if (max_faults && max_nid != p->numa_preferred_nid)
> + p->numa_preferred_nid = max_nid;
> }
>
> /*
> --
> 1.8.1.4
>
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WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 05/16] sched: Select a preferred node with the most numa hinting faults
Date: Thu, 11 Jul 2013 13:23:59 +0200 [thread overview]
Message-ID: <20130711112359.GG25631@dyad.programming.kicks-ass.net> (raw)
In-Reply-To: <1373536020-2799-6-git-send-email-mgorman@suse.de>
On Thu, Jul 11, 2013 at 10:46:49AM +0100, Mel Gorman wrote:
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1593,6 +1593,7 @@ static void __sched_fork(struct task_struct *p)
> p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
> p->numa_migrate_seq = p->mm ? p->mm->numa_scan_seq - 1 : 0;
> p->numa_scan_period = sysctl_numa_balancing_scan_delay;
> + p->numa_preferred_nid = -1;
(1)
> p->numa_work.next = &p->numa_work;
> p->numa_faults = NULL;
> #endif /* CONFIG_NUMA_BALANCING */
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 904fd6f..c0bee41 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -793,7 +793,8 @@ unsigned int sysctl_numa_balancing_scan_delay = 1000;
>
> static void task_numa_placement(struct task_struct *p)
> {
> - int seq;
> + int seq, nid, max_nid = 0;
Should you not start with max_nid = -1?
> + unsigned long max_faults = 0;
>
> if (!p->mm) /* for example, ksmd faulting in a user's mm */
> return;
> @@ -802,7 +803,19 @@ static void task_numa_placement(struct task_struct *p)
> return;
> p->numa_scan_seq = seq;
>
> - /* FIXME: Scheduling placement policy hints go here */
> + /* Find the node with the highest number of faults */
> + for (nid = 0; nid < nr_node_ids; nid++) {
> + unsigned long faults = p->numa_faults[nid];
> + p->numa_faults[nid] >>= 1;
> + if (faults > max_faults) {
> + max_faults = faults;
> + max_nid = nid;
> + }
> + }
> +
It is rather unlikely; but suppose the entire ->numa_faults[] array is 0, you'd
somehow end up selecting max_nid := 0. Which seems inconsistent with \1.
> + /* Update the tasks preferred node if necessary */
> + if (max_faults && max_nid != p->numa_preferred_nid)
> + p->numa_preferred_nid = max_nid;
> }
>
> /*
> --
> 1.8.1.4
>
next prev parent reply other threads:[~2013-07-11 11:24 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-11 9:46 [PATCH 0/16] Basic scheduler support for automatic NUMA balancing V4 Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 01/16] mm: numa: Document automatic NUMA balancing sysctls Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 02/16] sched: Track NUMA hinting faults on per-node basis Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 03/16] mm: numa: Account for THP numa hinting faults on the correct node Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 04/16] mm: numa: Do not migrate or account for hinting faults on the zero page Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 11:21 ` Peter Zijlstra
2013-07-11 11:21 ` Peter Zijlstra
2013-07-11 12:42 ` Mel Gorman
2013-07-11 12:42 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 05/16] sched: Select a preferred node with the most numa hinting faults Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 11:23 ` Peter Zijlstra [this message]
2013-07-11 11:23 ` Peter Zijlstra
2013-07-11 12:53 ` Mel Gorman
2013-07-11 12:53 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 06/16] sched: Update NUMA hinting faults once per scan Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 07/16] sched: Favour moving tasks towards the preferred node Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 08/16] sched: Reschedule task on preferred NUMA node once selected Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 12:30 ` Peter Zijlstra
2013-07-11 12:30 ` Peter Zijlstra
2013-07-11 13:03 ` Mel Gorman
2013-07-11 13:03 ` Mel Gorman
2013-07-11 13:11 ` Peter Zijlstra
2013-07-11 13:11 ` Peter Zijlstra
2013-07-11 14:09 ` Mel Gorman
2013-07-11 14:09 ` Mel Gorman
2013-07-12 10:14 ` Peter Zijlstra
2013-07-12 10:14 ` Peter Zijlstra
2013-07-12 10:28 ` Mel Gorman
2013-07-12 10:28 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 09/16] sched: Add infrastructure for split shared/private accounting of NUMA hinting faults Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 10/16] sched: Increase NUMA PTE scanning when a new preferred node is selected Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 11/16] sched: Check current->mm before allocating NUMA faults Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 12/16] sched: Set the scan rate proportional to the size of the task being scanned Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 13/16] mm: numa: Scan pages with elevated page_mapcount Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 14/16] sched: Remove check that skips small VMAs Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:46 ` [PATCH 15/16] sched: Set preferred NUMA node based on number of private faults Mel Gorman
2013-07-11 9:46 ` Mel Gorman
2013-07-11 9:47 ` [PATCH 16/16] sched: Select least loaded CPU on preferred NUMA node Mel Gorman
2013-07-11 9:47 ` Mel Gorman
2013-07-11 12:39 ` Peter Zijlstra
2013-07-11 12:39 ` Peter Zijlstra
2013-07-11 13:24 ` Mel Gorman
2013-07-11 13:24 ` Mel Gorman
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