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SubjectRe: [PATCH 08/18] sched: Reschedule task on preferred NUMA node once selected
On Thu, Aug 01, 2013 at 10:17:57AM +0530, Srikar Dronamraju wrote:
> * Mel Gorman <mgorman@suse.de> [2013-07-15 16:20:10]:
>
> > A preferred node is selected based on the node the most NUMA hinting
> > faults was incurred on. There is no guarantee that the task is running
> > on that node at the time so this patch rescheules the task to run on
> > the most idle CPU of the selected node when selected. This avoids
> > waiting for the balancer to make a decision.
> >
> > Signed-off-by: Mel Gorman <mgorman@suse.de>
> > ---
> > kernel/sched/core.c | 17 +++++++++++++++++
> > kernel/sched/fair.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
> > kernel/sched/sched.h | 1 +
> > 3 files changed, 63 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index 5e02507..b67a102 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -4856,6 +4856,23 @@ fail:
> > return ret;
> > }
> >
> > +#ifdef CONFIG_NUMA_BALANCING
> > +/* Migrate current task p to target_cpu */
> > +int migrate_task_to(struct task_struct *p, int target_cpu)
> > +{
> > + struct migration_arg arg = { p, target_cpu };
> > + int curr_cpu = task_cpu(p);
> > +
> > + if (curr_cpu == target_cpu)
> > + return 0;
> > +
> > + if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
> > + return -EINVAL;
> > +
> > + return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
>
> As I had noted earlier, this upsets schedstats badly.
> Can we add a TODO for this patch, which mentions that schedstats need to
> taken care.
>

I added a TODO comment because there is a possibility that this will all
change again with the stop_two_cpus patch.

--
Mel Gorman
SUSE Labs


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