From: Vincent Guittot <vincent.guittot@linaro.org>
To: linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org
Cc: pauld@redhat.com, valentin.schneider@arm.com,
srikar@linux.vnet.ibm.com, quentin.perret@arm.com,
dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com,
hdanton@sina.com, parth@linux.ibm.com, riel@surriel.com,
Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH v4 03/11] sched/fair: remove meaningless imbalance calculation
Date: Fri, 18 Oct 2019 15:26:30 +0200 [thread overview]
Message-ID: <1571405198-27570-4-git-send-email-vincent.guittot@linaro.org> (raw)
In-Reply-To: <1571405198-27570-1-git-send-email-vincent.guittot@linaro.org>
clean up load_balance and remove meaningless calculation and fields before
adding new algorithm.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Rik van Riel <riel@surriel.com>
---
kernel/sched/fair.c | 105 +---------------------------------------------------
1 file changed, 1 insertion(+), 104 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9a2aceb..e004841 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5390,18 +5390,6 @@ 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)
{
/*
@@ -7667,7 +7655,6 @@ 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 */
@@ -8049,9 +8036,6 @@ 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);
@@ -8282,76 +8266,6 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
}
/**
- * 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
@@ -8370,15 +8284,6 @@ 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
@@ -8389,7 +8294,7 @@ 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;
}
/*
@@ -8427,14 +8332,6 @@ 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 *********************/
--
2.7.4
next prev parent reply other threads:[~2019-10-18 13:26 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 13:26 [PATCH v4 00/10] sched/fair: rework the CFS load balance Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 01/11] sched/fair: clean up asym packing Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Clean " tip-bot2 for Vincent Guittot
2019-10-30 14:51 ` [PATCH v4 01/11] sched/fair: clean " Mel Gorman
2019-10-30 16:03 ` Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 02/11] sched/fair: rename sum_nr_running to sum_h_nr_running Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Rename sg_lb_stats::sum_nr_running " tip-bot2 for Vincent Guittot
2019-10-30 14:53 ` [PATCH v4 02/11] sched/fair: rename sum_nr_running " Mel Gorman
2019-10-18 13:26 ` Vincent Guittot [this message]
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Remove meaningless imbalance calculation tip-bot2 for Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 04/11] sched/fair: rework load_balance Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Rework load_balance() tip-bot2 for Vincent Guittot
2019-10-30 15:45 ` [PATCH v4 04/11] sched/fair: rework load_balance Mel Gorman
2019-10-30 16:16 ` Valentin Schneider
2019-10-31 9:09 ` Vincent Guittot
2019-10-31 10:15 ` Mel Gorman
2019-10-31 11:13 ` Vincent Guittot
2019-10-31 11:40 ` Mel Gorman
2019-11-08 16:35 ` Vincent Guittot
2019-11-08 18:37 ` Mel Gorman
2019-11-12 10:58 ` Vincent Guittot
2019-11-12 15:06 ` Mel Gorman
2019-11-12 15:40 ` Vincent Guittot
2019-11-12 17:45 ` Mel Gorman
2019-11-18 13:50 ` Ingo Molnar
2019-11-18 13:57 ` Vincent Guittot
2019-11-18 14:51 ` Mel Gorman
2019-10-18 13:26 ` [PATCH v4 05/11] sched/fair: use rq->nr_running when balancing load Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Use " tip-bot2 for Vincent Guittot
2019-10-30 15:54 ` [PATCH v4 05/11] sched/fair: use " Mel Gorman
2019-10-18 13:26 ` [PATCH v4 06/11] sched/fair: use load instead of runnable load in load_balance Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Use load instead of runnable load in load_balance() tip-bot2 for Vincent Guittot
2019-10-30 15:58 ` [PATCH v4 06/11] sched/fair: use load instead of runnable load in load_balance Mel Gorman
2019-10-18 13:26 ` [PATCH v4 07/11] sched/fair: evenly spread tasks when not overloaded Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Spread out tasks evenly " tip-bot2 for Vincent Guittot
2019-10-30 16:03 ` [PATCH v4 07/11] sched/fair: evenly spread tasks " Mel Gorman
2019-10-18 13:26 ` [PATCH v4 08/11] sched/fair: use utilization to select misfit task Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Use " tip-bot2 for Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 09/11] sched/fair: use load instead of runnable load in wakeup path Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Use " tip-bot2 for Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 10/11] sched/fair: optimize find_idlest_group Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Optimize find_idlest_group() tip-bot2 for Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 11/11] sched/fair: rework find_idlest_group Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Rework find_idlest_group() tip-bot2 for Vincent Guittot
2019-10-22 16:46 ` [PATCH] sched/fair: fix rework of find_idlest_group() Vincent Guittot
2019-10-23 7:50 ` Chen, Rong A
2019-10-30 16:07 ` Mel Gorman
2019-11-18 17:42 ` [tip: sched/core] sched/fair: Fix " tip-bot2 for Vincent Guittot
2019-11-22 14:37 ` [PATCH] sched/fair: fix " Valentin Schneider
2019-11-25 9:16 ` Vincent Guittot
2019-11-25 11:03 ` Valentin Schneider
2019-11-20 11:58 ` [PATCH v4 11/11] sched/fair: rework find_idlest_group Qais Yousef
2019-11-20 13:21 ` Vincent Guittot
2019-11-20 16:53 ` Vincent Guittot
2019-11-20 17:34 ` Qais Yousef
2019-11-20 17:43 ` Vincent Guittot
2019-11-20 18:10 ` Qais Yousef
2019-11-20 18:20 ` Vincent Guittot
2019-11-20 18:27 ` Qais Yousef
2019-11-20 19:28 ` Vincent Guittot
2019-11-20 19:55 ` Qais Yousef
2019-11-21 14:58 ` Qais Yousef
2019-11-22 14:34 ` Valentin Schneider
2019-11-25 9:59 ` Vincent Guittot
2019-11-25 11:13 ` Valentin Schneider
2019-10-21 7:50 ` [PATCH v4 00/10] sched/fair: rework the CFS load balance Ingo Molnar
2019-10-21 8:44 ` Vincent Guittot
2019-10-21 12:56 ` Phil Auld
2019-10-24 12:38 ` Phil Auld
2019-10-24 13:46 ` Phil Auld
2019-10-24 14:59 ` Vincent Guittot
2019-10-25 13:33 ` Phil Auld
2019-10-28 13:03 ` Vincent Guittot
2019-10-30 14:39 ` Phil Auld
2019-10-30 16:24 ` Dietmar Eggemann
2019-10-30 16:35 ` Valentin Schneider
2019-10-30 17:19 ` Phil Auld
2019-10-30 17:25 ` Valentin Schneider
2019-10-30 17:29 ` Phil Auld
2019-10-30 17:28 ` Vincent Guittot
2019-10-30 17:44 ` Phil Auld
2019-10-30 17:25 ` Vincent Guittot
2019-10-31 13:57 ` Phil Auld
2019-10-31 16:41 ` Vincent Guittot
2019-10-30 16:24 ` Mel Gorman
2019-10-30 16:35 ` Vincent Guittot
2019-11-18 13:15 ` Ingo Molnar
2019-11-25 12:48 ` Valentin Schneider
2020-01-03 16:39 ` Valentin Schneider
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