Re: [PATCH 2/2] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine

2018-02-12 Thread Mel Gorman
On Mon, Feb 12, 2018 at 06:37:43PM +0100, Peter Zijlstra wrote: > On Mon, Feb 12, 2018 at 05:11:31PM +, Mel Gorman wrote: > > +static void > > +update_wa_numa_placement(struct task_struct *p, int prev_cpu, int target) > > +{ > > + unsigned long interval; > > + > > + if (!static_branch_likel

Re: [PATCH 2/2] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine

2018-02-12 Thread Mel Gorman
On Mon, Feb 12, 2018 at 06:34:49PM +0100, Peter Zijlstra wrote: > On Mon, Feb 12, 2018 at 05:11:31PM +, Mel Gorman wrote: > > > However, the benefit in other cases is large. This is the result for NAS > > with the D class sizing on a 4-socket machine > > > > 4.15.0

Re: [PATCH 2/2] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine

2018-02-12 Thread Peter Zijlstra
On Mon, Feb 12, 2018 at 05:11:31PM +, Mel Gorman wrote: > +static void > +update_wa_numa_placement(struct task_struct *p, int prev_cpu, int target) > +{ > + unsigned long interval; > + > + if (!static_branch_likely(&sched_numa_balancing)) > + return; > + > + /* If balanc

Re: [PATCH 2/2] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine

2018-02-12 Thread Peter Zijlstra
On Mon, Feb 12, 2018 at 05:11:31PM +, Mel Gorman wrote: > However, the benefit in other cases is large. This is the result for NAS > with the D class sizing on a 4-socket machine > > 4.15.0 4.15.0 > sdnuma-v1r23 delayretry-v1

[PATCH 2/2] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine

2018-02-12 Thread Mel Gorman
If wake_affine pulls a task to another node for any reason and the node is no longer preferred then temporarily stop automatic NUMA balancing pulling the task back. Otherwise, tasks with a strong waker/wakee relationship may constantly fight automatic NUMA balancing over where a task should be plac