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author | Vincent Guittot <vincent.guittot@linaro.org> | 2019-10-18 15:26:30 +0200 |
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committer | Ingo Molnar <mingo@kernel.org> | 2019-10-21 09:40:53 +0200 |
commit | fcf0553db6f4c79387864f6e4ab4a891601f395e (patch) | |
tree | 661220b03a3ba9d66aa9734e5d015e279125b4c0 /kernel/sched/fair.c | |
parent | a34983470301018324f0110791da452fee1318c2 (diff) | |
download | linux-stable-fcf0553db6f4c79387864f6e4ab4a891601f395e.tar.gz linux-stable-fcf0553db6f4c79387864f6e4ab4a891601f395e.tar.bz2 linux-stable-fcf0553db6f4c79387864f6e4ab4a891601f395e.zip |
sched/fair: Remove meaningless imbalance calculation
Clean up load_balance() and remove meaningless calculation and fields before
adding a new algorithm.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: srikar@linux.vnet.ibm.com
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/1571405198-27570-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/fair.c')
-rw-r--r-- | kernel/sched/fair.c | 105 |
1 files changed, 1 insertions, 104 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ad8f16a411e1..a1bc04fff23c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5380,18 +5380,6 @@ static unsigned long capacity_of(int cpu) return cpu_rq(cpu)->cpu_capacity; } -static unsigned long cpu_avg_load_per_task(int cpu) -{ - struct rq *rq = cpu_rq(cpu); - unsigned long nr_running = READ_ONCE(rq->cfs.h_nr_running); - unsigned long load_avg = cpu_runnable_load(rq); - - if (nr_running) - return load_avg / nr_running; - - return 0; -} - static void record_wakee(struct task_struct *p) { /* @@ -7657,7 +7645,6 @@ static unsigned long task_h_load(struct task_struct *p) struct sg_lb_stats { unsigned long avg_load; /*Avg load across the CPUs of the group */ unsigned long group_load; /* Total load over the CPUs of the group */ - unsigned long load_per_task; unsigned long group_capacity; unsigned long group_util; /* Total utilization of the group */ unsigned int sum_h_nr_running; /* Nr of CFS tasks running in the group */ @@ -8039,9 +8026,6 @@ static inline void update_sg_lb_stats(struct lb_env *env, sgs->group_capacity = group->sgc->capacity; sgs->avg_load = (sgs->group_load*SCHED_CAPACITY_SCALE) / sgs->group_capacity; - if (sgs->sum_h_nr_running) - sgs->load_per_task = sgs->group_load / sgs->sum_h_nr_running; - sgs->group_weight = group->group_weight; sgs->group_no_capacity = group_is_overloaded(env, sgs); @@ -8272,76 +8256,6 @@ next_group: } /** - * fix_small_imbalance - Calculate the minor imbalance that exists - * amongst the groups of a sched_domain, during - * load balancing. - * @env: The load balancing environment. - * @sds: Statistics of the sched_domain whose imbalance is to be calculated. - */ -static inline -void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) -{ - unsigned long tmp, capa_now = 0, capa_move = 0; - unsigned int imbn = 2; - unsigned long scaled_busy_load_per_task; - struct sg_lb_stats *local, *busiest; - - local = &sds->local_stat; - busiest = &sds->busiest_stat; - - if (!local->sum_h_nr_running) - local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); - else if (busiest->load_per_task > local->load_per_task) - imbn = 1; - - scaled_busy_load_per_task = - (busiest->load_per_task * SCHED_CAPACITY_SCALE) / - busiest->group_capacity; - - if (busiest->avg_load + scaled_busy_load_per_task >= - local->avg_load + (scaled_busy_load_per_task * imbn)) { - env->imbalance = busiest->load_per_task; - return; - } - - /* - * OK, we don't have enough imbalance to justify moving tasks, - * however we may be able to increase total CPU capacity used by - * moving them. - */ - - capa_now += busiest->group_capacity * - min(busiest->load_per_task, busiest->avg_load); - capa_now += local->group_capacity * - min(local->load_per_task, local->avg_load); - capa_now /= SCHED_CAPACITY_SCALE; - - /* Amount of load we'd subtract */ - if (busiest->avg_load > scaled_busy_load_per_task) { - capa_move += busiest->group_capacity * - min(busiest->load_per_task, - busiest->avg_load - scaled_busy_load_per_task); - } - - /* Amount of load we'd add */ - if (busiest->avg_load * busiest->group_capacity < - busiest->load_per_task * SCHED_CAPACITY_SCALE) { - tmp = (busiest->avg_load * busiest->group_capacity) / - local->group_capacity; - } else { - tmp = (busiest->load_per_task * SCHED_CAPACITY_SCALE) / - local->group_capacity; - } - capa_move += local->group_capacity * - min(local->load_per_task, local->avg_load + tmp); - capa_move /= SCHED_CAPACITY_SCALE; - - /* Move if we gain throughput */ - if (capa_move > capa_now) - env->imbalance = busiest->load_per_task; -} - -/** * calculate_imbalance - Calculate the amount of imbalance present within the * groups of a given sched_domain during load balance. * @env: load balance environment @@ -8360,15 +8274,6 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s return; } - if (busiest->group_type == group_imbalanced) { - /* - * In the group_imb case we cannot rely on group-wide averages - * to ensure CPU-load equilibrium, look at wider averages. XXX - */ - busiest->load_per_task = - min(busiest->load_per_task, sds->avg_load); - } - /* * Avg load of busiest sg can be less and avg load of local sg can * be greater than avg load across all sgs of sd because avg load @@ -8379,7 +8284,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s (busiest->avg_load <= sds->avg_load || local->avg_load >= sds->avg_load)) { env->imbalance = 0; - return fix_small_imbalance(env, sds); + return; } /* @@ -8417,14 +8322,6 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s busiest->group_misfit_task_load); } - /* - * if *imbalance is less than the average load per runnable task - * there is no guarantee that any tasks will be moved so we'll have - * a think about bumping its value to force at least one task to be - * moved - */ - if (env->imbalance < busiest->load_per_task) - return fix_small_imbalance(env, sds); } /******* find_busiest_group() helpers end here *********************/ |