Lines Matching +full:always +full:- +full:running
1 .. SPDX-License-Identifier: GPL-2.0
57 foreground, top-app, etc. Util clamp can be used to constrain how much
60 the ones belonging to the currently active app (top-app group). Beside this
65 1. The big cores are free to run top-app tasks immediately. top-app
90 UCLAMP_MIN=1024 will ensure such tasks will always see the highest performance
91 level when they start running.
106 Note that by design RT tasks don't have per-task PELT signal and must always
109 Note that using schedutil always implies a single delay to modify the frequency
111 helps picking what frequency to request instead of schedutil always requesting
114 See :ref:`section 3.4 <uclamp-default-values>` for default values and
115 :ref:`3.4.1 <sched-util-clamp-min-rt-default>` on how to change RT tasks
150 task on the rq to only a subset of tasks on the top-most bucket.
157 uclamp value of the rq. See :ref:`section 2.1 <uclamp-buckets>` for details on
182 .. _uclamp-buckets:
185 ------------
195 +-----------+-----------+-----------+---- ----+-----------+
197 +-----------+-----------+-----------+---- ----+-----------+
199 +- p0 +- p3 +- p4
201 +- p1 +- p5
203 +- p2
234 p->uclamp[UCLAMP_MIN] = 300
235 p->uclamp[UCLAMP_MAX] = 1024
249 rq->uclamp[UCLAMP_MIN] = max(rq->uclamp[UCLAMP_MIN], p->uclamp[UCLAMP_MIN])
257 rq->uclamp[UCLAMP_MIN] = search_top_bucket_for_highest_value()
261 See :ref:`section 3.4 <uclamp-default-values>` for details on default values.
265 --------------------
279 p0->uclamp[UCLAMP_MIN] = 300
280 p0->uclamp[UCLAMP_MAX] = 900
282 p1->uclamp[UCLAMP_MIN] = 500
283 p1->uclamp[UCLAMP_MAX] = 500
290 rq->uclamp[UCLAMP_MIN] = max(300, 500) = 500
291 rq->uclamp[UCLAMP_MAX] = max(900, 500) = 900
293 As we shall see in :ref:`section 5.1 <uclamp-capping-fail>`, this max
298 -----------------------------
311 :ref:`Section 3 <uclamp-interfaces>` discusses the interfaces and will expand
328 ----------
335 .. _uclamp-interfaces:
341 -----------------------
346 at when this task is running. Or lower performance bound.
348 at when this task is running. Or upper performance bound.
354 attr->sched_util_min = 40% * 1024;
355 attr->sched_util_max = 80% * 1024;
357 When task @p is running, **the scheduler should try its best to ensure it
362 The special value -1 is used to reset the uclamp settings to the system
365 Note that resetting the uclamp value to system default using -1 is not the same
372 ---------------------
382 * cpu.uclamp.min is a protection as described in :ref:`section 3-3 of cgroup
383 v2 documentation <cgroupv2-protections-distributor>`.
391 * cpu.uclamp.max is a limit as described in :ref:`section 3-2 of cgroup v2
392 documentation <cgroupv2-limits-distributor>`.
404 p0->uclamp[UCLAMP_MIN] = // system default;
405 p0->uclamp[UCLAMP_MAX] = // system default;
407 p1->uclamp[UCLAMP_MIN] = 40% * 1024;
408 p1->uclamp[UCLAMP_MAX] = 50% * 1024;
410 cgroup0->cpu.uclamp.min = 20% * 1024;
411 cgroup0->cpu.uclamp.max = 60% * 1024;
413 cgroup1->cpu.uclamp.min = 60% * 1024;
414 cgroup1->cpu.uclamp.max = 100% * 1024;
420 p0->uclamp[UCLAMP_MIN] = cgroup0->cpu.uclamp.min = 20% * 1024;
421 p0->uclamp[UCLAMP_MAX] = cgroup0->cpu.uclamp.max = 60% * 1024;
423 p1->uclamp[UCLAMP_MIN] = 40% * 1024; // intact
424 p1->uclamp[UCLAMP_MAX] = 50% * 1024; // intact
430 p0->uclamp[UCLAMP_MIN] = cgroup1->cpu.uclamp.min = 60% * 1024;
431 p0->uclamp[UCLAMP_MAX] = cgroup1->cpu.uclamp.max = 100% * 1024;
433 p1->uclamp[UCLAMP_MIN] = cgroup1->cpu.uclamp.min = 60% * 1024;
434 p1->uclamp[UCLAMP_MAX] = 50% * 1024; // intact
440 ---------------------
443 --------------------------
451 they won't be satisfied until it is more than p->uclamp[UCLAMP_MIN].
456 --------------------------
467 For example, it can be handy to limit performance when running low on battery
472 won't be satisfied until it is more than p->uclamp[UCLAMP_MAX].
476 .. _uclamp-default-values:
479 -------------------
485 p_fair->uclamp[UCLAMP_MIN] = 0
486 p_fair->uclamp[UCLAMP_MAX] = 1024
496 p_rt->uclamp[UCLAMP_MIN] = 1024
497 p_rt->uclamp[UCLAMP_MAX] = 1024
505 .. _sched-util-clamp-min-rt-default:
508 -------------------------------------
510 Running RT tasks at maximum performance point is expensive on battery powered
514 address the system requirement without burning power running at maximum
531 application is running on and to use it in conjunction with a feedback loop to
543 4.1. Boost important and DVFS-latency-sensitive tasks
544 -----------------------------------------------------
564 -------------------------
571 -------------------
581 4.4. Per-app performance restriction
582 ------------------------------------
597 .. _uclamp-capping-fail:
600 ---------------------------------------------------------------------
606 p0->uclamp[UCLAMP_MAX] = 512
612 p1->uclamp[UCLAMP_MAX] = 1024
619 rq->uclamp[UCLAMP_MAX] = max(512, 1024) = 1024
625 both are running at the same rq, p1 will cause the frequency capping to be left
630 ------------------------------------------------
632 PELT assumes that frequency will always increase as the signals grow to ensure
633 there's always some idle time on the CPU. But with UCLAMP_MAX, this frequency
645 p0->util_avg = 300
646 p0->uclamp[UCLAMP_MAX] = 0
655 rq->uclamp[UCLAMP_MAX] = 0
665 long as there's idle time, p->util_avg updates will be off by a some margin,
670 p0->util_avg = 300 + small_error
683 p0->util_avg = 1024
689 p1->util_avg = 200
690 p1->uclamp[UCLAMP_MAX] = 1024
693 aggregation rule. But since the capped p0 task was running and throttled
694 severely, then the rq->util_avg will be:
698 p0->util_avg = 1024
699 p1->util_avg = 200
701 rq->util_avg = 1024
702 rq->uclamp[UCLAMP_MAX] = 1024
708 p0->util_avg = 300
709 p1->util_avg = 200
711 rq->util_avg = 500
716 -----------------------------------
720 1. Hardware takes non-zero time to respond to any frequency change
722 2. Non fast-switch systems require a worker deadline thread to wake up
728 performance point when it wakes up and starts running, then all these