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([2a01:e0a:f:6020:1563:65bf:c344:661e]) by smtp.gmail.com with ESMTPSA id q4-20020adfdfc4000000b002bc6c180738sm14586348wrn.90.2023.01.13.05.40.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Jan 2023 05:40:58 -0800 (PST) From: Vincent Guittot To: mingo@kernel.org, peterz@infradead.org, dietmar.eggemann@arm.com, qyousef@layalina.io, rafael@kernel.org, viresh.kumar@linaro.org, vschneid@redhat.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: lukasz.luba@arm.com, wvw@google.com, xuewen.yan94@gmail.com, han.lin@mediatek.com, Jonathan.JMChen@mediatek.com, Vincent Guittot Subject: [PATCH v3] sched/fair: unlink misfit task from cpu overutilized Date: Fri, 13 Jan 2023 14:40:56 +0100 Message-Id: <20230113134056.257691-1-vincent.guittot@linaro.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" By taking into account uclamp_min, the 1:1 relation between task misfit and cpu overutilized is no more true as a task with a small util_avg of may not fit a high capacity cpu because of uclamp_min constraint. Add a new state in util_fits_cpu() to reflect the case that task would fit a CPU except for the uclamp_min hint which is a performance requirement. Use -1 to reflect that a CPU doesn't fit only because of uclamp_min so we can use this new value to take additional action to select the best CPU that doesn't match uclamp_min hint. Signed-off-by: Vincent Guittot --- Change since v2: - fix a condition in feec() - add comments kernel/sched/fair.c | 108 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 83 insertions(+), 25 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e9d906a9bba9..29adb9e27b3d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4525,8 +4525,7 @@ static inline int util_fits_cpu(unsigned long util, * 2. The system is being saturated when we're operating near * max capacity, it doesn't make sense to block overutilized. */ - uclamp_max_fits =3D (capacity_orig =3D=3D SCHED_CAPACITY_SCALE) && (uclam= p_max =3D=3D SCHED_CAPACITY_SCALE); - uclamp_max_fits =3D !uclamp_max_fits && (uclamp_max <=3D capacity_orig); + uclamp_max_fits =3D (uclamp_max <=3D capacity_orig) || (capacity_orig =3D= =3D SCHED_CAPACITY_SCALE); fits =3D fits || uclamp_max_fits; =20 /* @@ -4561,8 +4560,8 @@ static inline int util_fits_cpu(unsigned long util, * handle the case uclamp_min > uclamp_max. */ uclamp_min =3D min(uclamp_min, uclamp_max); - if (util < uclamp_min && capacity_orig !=3D SCHED_CAPACITY_SCALE) - fits =3D fits && (uclamp_min <=3D capacity_orig_thermal); + if (fits && (util < uclamp_min) && (uclamp_min > capacity_orig_thermal)) + return -1; =20 return fits; } @@ -4572,7 +4571,11 @@ static inline int task_fits_cpu(struct task_struct *= p, int cpu) unsigned long uclamp_min =3D uclamp_eff_value(p, UCLAMP_MIN); unsigned long uclamp_max =3D uclamp_eff_value(p, UCLAMP_MAX); unsigned long util =3D task_util_est(p); - return util_fits_cpu(util, uclamp_min, uclamp_max, cpu); + /* + * Return true only if the cpu fully fits the task requirements, which + * include the utilization but also the performance. + */ + return (util_fits_cpu(util, uclamp_min, uclamp_max, cpu) > 0); } =20 static inline void update_misfit_status(struct task_struct *p, struct rq *= rq) @@ -6132,6 +6135,7 @@ static inline bool cpu_overutilized(int cpu) unsigned long rq_util_min =3D uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN); unsigned long rq_util_max =3D uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX); =20 + /* Return true only if the utlization doesn't fit its capacity */ return !util_fits_cpu(cpu_util_cfs(cpu), rq_util_min, rq_util_max, cpu); } =20 @@ -6925,6 +6929,7 @@ static int select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int t= arget) { unsigned long task_util, util_min, util_max, best_cap =3D 0; + int fits, best_fits =3D 0; int cpu, best_cpu =3D -1; struct cpumask *cpus; =20 @@ -6940,12 +6945,28 @@ select_idle_capacity(struct task_struct *p, struct = sched_domain *sd, int target) =20 if (!available_idle_cpu(cpu) && !sched_idle_cpu(cpu)) continue; - if (util_fits_cpu(task_util, util_min, util_max, cpu)) + + fits =3D util_fits_cpu(task_util, util_min, util_max, cpu); + + /* This CPU fits with all capacity and performance requirements */ + if (fits > 0) return cpu; + /* + * Only the min performance (i.e. uclamp_min) doesn't fit. Look + * for the CPU with highest performance capacity. + */ + else if (fits < 0) + cpu_cap =3D capacity_orig_of(cpu) - thermal_load_avg(cpu_rq(cpu)); =20 - if (cpu_cap > best_cap) { + /* + * First, select cpu which fits better (-1 being better than 0). + * Then, select the one with largest capacity at same level. + */ + if ((fits < best_fits) || + ((fits =3D=3D best_fits) && (cpu_cap > best_cap))) { best_cap =3D cpu_cap; best_cpu =3D cpu; + best_fits =3D fits; } } =20 @@ -6958,7 +6979,11 @@ static inline bool asym_fits_cpu(unsigned long util, int cpu) { if (sched_asym_cpucap_active()) - return util_fits_cpu(util, util_min, util_max, cpu); + /* + * Return true only if the cpu fully fits the task requirements + * which include the utilization but also the performance. + */ + return (util_fits_cpu(util, util_min, util_max, cpu) > 0); =20 return true; } @@ -7325,6 +7350,9 @@ static int find_energy_efficient_cpu(struct task_stru= ct *p, int prev_cpu) unsigned long p_util_max =3D uclamp_is_used() ? uclamp_eff_value(p, UCLAM= P_MAX) : 1024; struct root_domain *rd =3D this_rq()->rd; int cpu, best_energy_cpu, target =3D -1; + int prev_fits =3D -1, best_fits =3D -1; + unsigned long best_thermal_cap =3D 0; + unsigned long prev_thermal_cap =3D 0; struct sched_domain *sd; struct perf_domain *pd; struct energy_env eenv; @@ -7360,6 +7388,7 @@ static int find_energy_efficient_cpu(struct task_stru= ct *p, int prev_cpu) unsigned long prev_spare_cap =3D 0; int max_spare_cap_cpu =3D -1; unsigned long base_energy; + int fits, max_fits =3D -1; =20 cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask); =20 @@ -7412,7 +7441,9 @@ static int find_energy_efficient_cpu(struct task_stru= ct *p, int prev_cpu) util_max =3D max(rq_util_max, p_util_max); } } - if (!util_fits_cpu(util, util_min, util_max, cpu)) + + fits =3D util_fits_cpu(util, util_min, util_max, cpu); + if (!fits) continue; =20 lsub_positive(&cpu_cap, util); @@ -7420,7 +7451,9 @@ static int find_energy_efficient_cpu(struct task_stru= ct *p, int prev_cpu) if (cpu =3D=3D prev_cpu) { /* Always use prev_cpu as a candidate. */ prev_spare_cap =3D cpu_cap; - } else if (cpu_cap > max_spare_cap) { + prev_fits =3D fits; + } else if ((fits > max_fits) || + ((fits =3D=3D max_fits) && (cpu_cap > max_spare_cap))) { /* * Find the CPU with the maximum spare capacity * among the remaining CPUs in the performance @@ -7428,6 +7461,7 @@ static int find_energy_efficient_cpu(struct task_stru= ct *p, int prev_cpu) */ max_spare_cap =3D cpu_cap; max_spare_cap_cpu =3D cpu; + max_fits =3D fits; } } =20 @@ -7446,26 +7480,50 @@ static int find_energy_efficient_cpu(struct task_st= ruct *p, int prev_cpu) if (prev_delta < base_energy) goto unlock; prev_delta -=3D base_energy; + prev_thermal_cap =3D cpu_thermal_cap; best_delta =3D min(best_delta, prev_delta); } =20 /* Evaluate the energy impact of using max_spare_cap_cpu. */ if (max_spare_cap_cpu >=3D 0 && max_spare_cap > prev_spare_cap) { + /* Current best energy cpu fits better */ + if (max_fits < best_fits) + continue; + + /* + * Both don't fit performance (i.e. uclamp_min) but + * best energy cpu has better performance. + */ + if ((max_fits < 0) && + (cpu_thermal_cap <=3D best_thermal_cap)) + continue; + cur_delta =3D compute_energy(&eenv, pd, cpus, p, max_spare_cap_cpu); /* CPU utilization has changed */ if (cur_delta < base_energy) goto unlock; cur_delta -=3D base_energy; - if (cur_delta < best_delta) { - best_delta =3D cur_delta; - best_energy_cpu =3D max_spare_cap_cpu; - } + + /* + * Both fit for the task but best energy cpu has lower + * energy impact. + */ + if ((max_fits > 0) && (best_fits > 0) && + (cur_delta >=3D best_delta)) + continue; + + best_delta =3D cur_delta; + best_energy_cpu =3D max_spare_cap_cpu; + best_fits =3D max_fits; + best_thermal_cap =3D cpu_thermal_cap; } } rcu_read_unlock(); =20 - if (best_delta < prev_delta) + if ((best_fits > prev_fits) || + ((best_fits > 0) && (best_delta < prev_delta)) || + ((best_fits < 0) && (best_thermal_cap > prev_thermal_cap))) target =3D best_energy_cpu; =20 return target; @@ -10259,24 +10317,23 @@ static struct sched_group *find_busiest_group(str= uct lb_env *env) */ update_sd_lb_stats(env, &sds); =20 - if (sched_energy_enabled()) { - struct root_domain *rd =3D env->dst_rq->rd; - - if (rcu_dereference(rd->pd) && !READ_ONCE(rd->overutilized)) - goto out_balanced; - } - - local =3D &sds.local_stat; - busiest =3D &sds.busiest_stat; - /* There is no busy sibling group to pull tasks from */ if (!sds.busiest) goto out_balanced; =20 + busiest =3D &sds.busiest_stat; + /* Misfit tasks should be dealt with regardless of the avg load */ if (busiest->group_type =3D=3D group_misfit_task) goto force_balance; =20 + if (sched_energy_enabled()) { + struct root_domain *rd =3D env->dst_rq->rd; + + if (rcu_dereference(rd->pd) && !READ_ONCE(rd->overutilized)) + goto out_balanced; + } + /* ASYM feature bypasses nice load balance check */ if (busiest->group_type =3D=3D group_asym_packing) goto force_balance; @@ -10289,6 +10346,7 @@ static struct sched_group *find_busiest_group(struc= t lb_env *env) if (busiest->group_type =3D=3D group_imbalanced) goto force_balance; =20 + local =3D &sds.local_stat; /* * If the local group is busier than the selected busiest group * don't try and pull any tasks. --=20 2.34.1