sched: Prevent to re-select dst-cpu in load_balance()
Commit 88b8dac0
makes load_balance() consider other cpus in its
group. But, in that, there is no code for preventing to
re-select dst-cpu. So, same dst-cpu can be selected over and
over.
This patch add functionality to load_balance() in order to
exclude cpu which is selected once. We prevent to re-select
dst_cpu via env's cpus, so now, env's cpus is a candidate not
only for src_cpus, but also dst_cpus.
With this patch, we can remove lb_iterations and
max_lb_iterations, because we decide whether we can go ahead or
not via env's cpus.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Jason Low <jason.low2@hp.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1366705662-3587-7-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
e6252c3ef4
commit
e02e60c109
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@ -3905,7 +3905,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
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return 0;
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return 0;
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if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
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if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
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int new_dst_cpu;
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int cpu;
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schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
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schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
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@ -3920,12 +3920,15 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
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if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
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if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
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return 0;
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return 0;
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new_dst_cpu = cpumask_first_and(env->dst_grpmask,
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/* Prevent to re-select dst_cpu via env's cpus */
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tsk_cpus_allowed(p));
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for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
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if (new_dst_cpu < nr_cpu_ids) {
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if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) {
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env->flags |= LBF_SOME_PINNED;
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env->flags |= LBF_SOME_PINNED;
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env->new_dst_cpu = new_dst_cpu;
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env->new_dst_cpu = cpu;
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break;
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}
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}
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}
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return 0;
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return 0;
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}
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}
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@ -5008,7 +5011,6 @@ static int load_balance(int this_cpu, struct rq *this_rq,
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int *balance)
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int *balance)
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{
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{
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int ld_moved, cur_ld_moved, active_balance = 0;
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int ld_moved, cur_ld_moved, active_balance = 0;
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int lb_iterations, max_lb_iterations;
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struct sched_group *group;
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struct sched_group *group;
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struct rq *busiest;
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struct rq *busiest;
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unsigned long flags;
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unsigned long flags;
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@ -5028,15 +5030,8 @@ static int load_balance(int this_cpu, struct rq *this_rq,
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* For NEWLY_IDLE load_balancing, we don't need to consider
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* For NEWLY_IDLE load_balancing, we don't need to consider
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* other cpus in our group
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* other cpus in our group
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*/
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*/
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if (idle == CPU_NEWLY_IDLE) {
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if (idle == CPU_NEWLY_IDLE)
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env.dst_grpmask = NULL;
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env.dst_grpmask = NULL;
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/*
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* we don't care max_lb_iterations in this case,
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* in following patch, this will be removed
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*/
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max_lb_iterations = 0;
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} else
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max_lb_iterations = cpumask_weight(env.dst_grpmask);
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cpumask_copy(cpus, cpu_active_mask);
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cpumask_copy(cpus, cpu_active_mask);
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@ -5064,7 +5059,6 @@ redo:
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schedstat_add(sd, lb_imbalance[idle], env.imbalance);
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schedstat_add(sd, lb_imbalance[idle], env.imbalance);
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ld_moved = 0;
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ld_moved = 0;
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lb_iterations = 1;
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if (busiest->nr_running > 1) {
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if (busiest->nr_running > 1) {
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/*
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/*
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* Attempt to move tasks. If find_busiest_group has found
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* Attempt to move tasks. If find_busiest_group has found
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@ -5121,14 +5115,17 @@ more_balance:
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* moreover subsequent load balance cycles should correct the
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* moreover subsequent load balance cycles should correct the
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* excess load moved.
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* excess load moved.
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*/
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*/
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if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0 &&
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if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) {
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lb_iterations++ < max_lb_iterations) {
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env.dst_rq = cpu_rq(env.new_dst_cpu);
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env.dst_rq = cpu_rq(env.new_dst_cpu);
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env.dst_cpu = env.new_dst_cpu;
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env.dst_cpu = env.new_dst_cpu;
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env.flags &= ~LBF_SOME_PINNED;
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env.flags &= ~LBF_SOME_PINNED;
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env.loop = 0;
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env.loop = 0;
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env.loop_break = sched_nr_migrate_break;
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env.loop_break = sched_nr_migrate_break;
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/* Prevent to re-select dst_cpu via env's cpus */
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cpumask_clear_cpu(env.dst_cpu, env.cpus);
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/*
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/*
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* Go back to "more_balance" rather than "redo" since we
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* Go back to "more_balance" rather than "redo" since we
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* need to continue with same src_cpu.
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* need to continue with same src_cpu.
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