Messages in this thread Patch in this message | | | Date | Mon, 19 Feb 2018 14:56:44 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/7] sched/fair: Add group_misfit_task load-balance type |
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On Thu, Feb 15, 2018 at 04:20:49PM +0000, Morten Rasmussen wrote: > @@ -6733,9 +6758,12 @@ done: __maybe_unused > if (hrtick_enabled(rq)) > hrtick_start_fair(rq, p); > > + update_misfit_status(p, rq); > + > return p; > > idle: > + update_misfit_status(NULL, rq); > new_tasks = idle_balance(rq, rf); > > /*
So we set a point when picking a task (or tick). We clear said pointer when idle.
> @@ -7822,6 +7855,10 @@ static inline void update_sg_lb_stats(struct lb_env *env, > */ > if (!nr_running && idle_cpu(i)) > sgs->idle_cpus++; > + > + if (env->sd->flags & SD_ASYM_CPUCAPACITY && > + !sgs->group_misfit_task_load && rq->misfit_task_load) > + sgs->group_misfit_task_load = rq->misfit_task_load; > } > > /* Adjust by relative CPU capacity of the group */
And we read said pointer from another CPU, without holding the respective rq->lock.
What happens, if right after we set sgs->group_misfit_task_load, our task decides to exit?
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