* Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote: > From: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> > > On some Intel cores, they can boosted to a higher turbo frequency than > the other cores on the same die. So we prefer processes to be run on > them vs other lower frequency ones for extra performance. > > We extend the asym packing feature in the scheduler to support packing > task to the higher frequency core at the core sched domain level. > > We set up a core priority metric to abstract the core preferences based > on the maximum boost frequency. The priority is instantiated such that > the core with a higher priority is favored over the core with lower > priority when making scheduling decision using ASYM_PACKING. The smt > threads that are of higher number are discounted in their priority so > we will not try to pack tasks onto all the threads of a favored core > before using other cpu cores. The cpu that's of the highese priority > in a sched_group is recorded in sched_group->asym_prefer_cpu during > initialization to save lookup during load balancing. > > A sysctl variable /proc/sys/kernel/sched_itmt_enabled is provided so > the scheduling based on favored core can be turned on or off at run time. > +/* > + * Boolean to control whether we want to move processes to cpu capable > + * of higher turbo frequency for cpus supporting Intel Turbo Boost Max > + * Technology 3.0. > + * > + * It can be set via /proc/sys/kernel/sched_itmt_enabled > + */ > +unsigned int __read_mostly sysctl_sched_itmt_enabled = 0; Ugh, no. We don't add features to the scheduler in the hope that they might or might not help. We either enable a new feature by default (and make damn sure it helps!), or don't add the feature at all. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
