From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: riel@redhat.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, chegu_vinod@hp.com, mgorman@suse.de,
mingo@redhat.com
Subject: Re: [PATCH 4/7] numa,sched: tracepoints for NUMA balancing active nodemask changes
Date: Mon, 20 Jan 2014 14:05:51 -0500 [thread overview]
Message-ID: <20140120140551.3343ab2b@gandalf.local.home> (raw)
In-Reply-To: <20140120165205.GJ31570@twins.programming.kicks-ass.net>
On Mon, 20 Jan 2014 17:52:05 +0100
Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, Jan 17, 2014 at 04:12:06PM -0500, riel@redhat.com wrote:
> > From: Rik van Riel <riel@redhat.com>
> >
> > +++ 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
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next prev parent reply other threads:[~2014-01-20 19:05 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-17 21:12 [PATCH v2 0/7] pseudo-interleaving for automatic NUMA balancing riel
2014-01-17 21:12 ` [PATCH 1/7] numa,sched,mm: remove p->numa_migrate_deferred riel
2014-01-17 21:12 ` [PATCH 2/7] numa,sched: track from which nodes NUMA faults are triggered riel
2014-01-17 21:12 ` [PATCH 3/7] numa,sched: build per numa_group active node mask from faults_from statistics riel
2014-01-20 16:31 ` Peter Zijlstra
2014-01-20 18:55 ` Rik van Riel
2014-01-20 16:55 ` Peter Zijlstra
2014-01-17 21:12 ` [PATCH 4/7] numa,sched: tracepoints for NUMA balancing active nodemask changes riel
2014-01-20 16:52 ` Peter Zijlstra
2014-01-20 18:51 ` Rik van Riel
2014-01-20 19:05 ` Steven Rostedt [this message]
2014-01-17 21:12 ` [PATCH 5/7] numa,sched,mm: use active_nodes nodemask to limit numa migrations riel
2014-01-17 21:12 ` [PATCH 6/7] numa,sched: normalize faults_from stats and weigh by CPU use riel
2014-01-20 16:57 ` Peter Zijlstra
2014-01-20 19:02 ` Rik van Riel
2014-01-20 19:10 ` Peter Zijlstra
2014-01-17 21:12 ` [PATCH 7/7] numa,sched: do statistics calculation using local variables only riel
2014-01-18 3:31 ` Rik van Riel
2014-01-18 22:05 ` [PATCH v2 0/7] pseudo-interleaving for automatic NUMA balancing Chegu Vinod
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