schedstats additions
PATCH 1/1 schedstats additions
Hi,
I have a patch here to provide more useful statistics for me. Basically it moves a lot more of the balancing information into the domains instead of the runqueue, where it is nearly useless on multi-domain setups (eg. SMT+SMP, SMP+NUMA).
It requires a version number bump, but that isn't much of an issue because I think we're about the only two using it at the moment. But your tools will need a little bit of work.
What do you think?
---
linux-2.6-npiggin/kernel/sched.c | 155 ++++++++++++++++++++------------------- 1 files changed, 82 insertions(+), 73 deletions(-)
kernel/sched.c renamed from kernel/sched.c~sched-stat +82 -73
@@ -194,7 +194,6 @@ struct runqueue {unsigned long yld_cnt;/* schedule() stats */ -unsigned long sched_noswitch;unsigned long sched_switch;unsigned long sched_cnt;unsigned long sched_goidle;
@@ -203,26 +202,9 @@ struct runqueue {unsigned long pt_gained[MAX_IDLE_TYPES ];unsigned long pt_lost[MAX_IDLE_TYPES ]; -/* active_load_balance() stats */ -unsigned long alb_cnt; -unsigned long alb_lost; -unsigned long alb_gained; -unsigned long alb_failed; -/* try_to_wake_up() stats */ unsigned long ttwu_cnt; -unsigned long ttwu_attempts; -unsigned long ttwu_moved; - -/* wake_up_new_task() stats */ -unsigned long wunt_cnt; -unsigned long wunt_moved; - -/* sched_migrate_task() stats */ -unsigned long smt_cnt; - -/* sched_balance_exec() stats */ -unsigned long sbe_cnt; +unsigned long ttwu_remote;#endif };
@@ -277,15 +259,24 @@ struct sched_domain {/* load_balance() stats */ unsigned long lb_cnt[MAX_IDLE_TYPES ];unsigned long lb_failed[MAX_IDLE_TYPES ]; +unsigned long lb_balanced[MAX_IDLE_TYPES ];unsigned long lb_imbalance[MAX_IDLE_TYPES ]; +unsigned long lb_pulled[MAX_IDLE_TYPES ]; +unsigned long lb_hot_pulled[MAX_IDLE_TYPES ];unsigned long lb_nobusyg[MAX_IDLE_TYPES ];unsigned long lb_nobusyq[MAX_IDLE_TYPES ]; +/* Active load balancing */ +unsigned long alb_cnt; +unsigned long alb_failed; +unsigned long alb_pushed; +/* sched_balance_exec() stats */ unsigned long sbe_attempts;unsigned long sbe_pushed;/* try_to_wake_up() stats */ +unsigned long ttwu_wake_remote;unsigned long ttwu_wake_affine;unsigned long ttwu_wake_balance;#endif
@@ -409,7 +400,7 @@ static inline void task_rq_unlock(runque* bump this up when changing the output format or the meaning of an existing * format, so that tools can adapt (or abort) */ -#define SCHEDSTAT_VERSION 10 +#define SCHEDSTAT_VERSION 11static int show_schedstat (struct seq_file *seq,void *v) {
@@ -427,17 +418,12 @@ static int show_schedstat(struct seq_fil/* runqueue-specific stats */ seq_printf (seq, -"cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu " -"%lu %lu %lu %lu %lu %lu %lu %lu %lu %lu" , +"cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu" , cpu, rq->yld_both_empty, - rq->yld_act_empty, rq->yld_exp_empty, - rq->yld_cnt, rq->sched_noswitch, + rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt, rq->sched_switch, rq->sched_cnt, rq->sched_goidle, - rq->alb_cnt, rq->alb_gained, rq->alb_lost, - rq->alb_failed, - rq->ttwu_cnt, rq->ttwu_moved, rq->ttwu_attempts, - rq->wunt_cnt, rq->wunt_moved, - rq->smt_cnt, rq->sbe_cnt, rq->rq_sched_info.cpu_time, + rq->ttwu_cnt, rq->ttwu_remote, + rq->rq_sched_info.cpu_time, rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);for (itype =IDLE ; itype <MAX_IDLE_TYPES ; itype++)
@@ -453,16 +439,20 @@ static int show_schedstat(struct seq_filcpumask_scnprintf (mask_str,NR_CPUS , sd->span);seq_printf (seq,"domain%d %s" , dcnt++, mask_str);for (itype =IDLE ; itype <MAX_IDLE_TYPES ; itype++) { -seq_printf (seq," %lu %lu %lu %lu %lu" , +seq_printf (seq," %lu %lu %lu %lu %lu %lu %lu %lu" , sd->lb_cnt[itype], + sd->lb_balanced[itype], sd->lb_failed[itype], sd->lb_imbalance[itype], + sd->lb_pulled[itype], + sd->lb_hot_pulled[itype], sd->lb_nobusyq[itype], sd->lb_nobusyg[itype]); } -seq_printf (seq," %lu %lu %lu %lu\n" , +seq_printf (seq," %lu %lu %lu %lu %lu %lu %lu %lu\n" , + sd->alb_cnt, sd->alb_failed, sd->alb_pushed, sd->sbe_pushed, sd->sbe_attempts, - sd->ttwu_wake_affine, sd->ttwu_wake_balance); + sd->ttwu_wake_remote, sd->ttwu_wake_affine, sd->ttwu_wake_balance); }#endif }
@@ -1058,6 +1048,10 @@ static int try_to_wake_up(task_t * p, ununsigned long load, this_load;struct sched_domain *sd;int new_cpu; + +#ifdef CONFIG_SCHEDSTATS +struct sched_domain *stat_sd =NULL ; +#endif #endif rq =task_rq_lock (p, &flags);
@@ -1076,8 +1070,19 @@ static int try_to_wake_up(task_t * p, unif (unlikely (task_running (rq, p))) goto out_activate; - new_cpu = cpu; +#ifdef CONFIG_SCHEDSTATS +if (cpu != this_cpu) { +schedstat_inc (rq, ttwu_remote); +for_each_domain (this_cpu, stat_sd) { +if (cpu_isset (cpu, stat_sd->span)) { +schedstat_inc (stat_sd, ttwu_wake_remote); +break ; + } + } + } +#endif + new_cpu = cpu;if (cpu == this_cpu ||unlikely (!cpu_isset (this_cpu, p->cpus_allowed))) goto out_set_cpu;
@@ -1103,30 +1108,32 @@ static int try_to_wake_up(task_t * p, un*/ for_each_domain (this_cpu, sd) {unsigned int imbalance; -/* -* Start passive balancing when half the imbalance_pct -* limit is reached. -*/ - imbalance = sd->imbalance_pct + (sd->imbalance_pct -100 ) /2 ; -if ((sd->flags &SD_WAKE_AFFINE ) && - !task_hot (p, rq->timestamp_last_tick, sd)) { +if (cpu_isset (cpu, sd->span)) {/* -* This domain has SD_WAKE_AFFINE and p is cache cold -* in this domain. +* Start passive balancing when half the imbalance_pct +* limit is reached. */ -if (cpu_isset (cpu, sd->span)) { -schedstat_inc (sd, ttwu_wake_affine); +if ((sd->flags &SD_WAKE_AFFINE ) && + !task_hot (p, rq->timestamp_last_tick, sd)) { +/* +* This domain has SD_WAKE_AFFINE and p is +* cache cold in this domain. +*/ +schedstat_inc (stat_sd, ttwu_wake_affine); goto out_set_cpu; } - }else if ((sd->flags &SD_WAKE_BALANCE ) && + + imbalance = sd->imbalance_pct + + (sd->imbalance_pct -100 ) /2 ; + +if ((sd->flags &SD_WAKE_BALANCE ) && imbalance*this_load <=100 *load) { -/* -* This domain has SD_WAKE_BALANCE and there is -* an imbalance. -*/ -if (cpu_isset (cpu, sd->span)) { -schedstat_inc (sd, ttwu_wake_balance); +/* +* This domain has SD_WAKE_BALANCE and there is +* an imbalance. +*/ +schedstat_inc (stat_sd, ttwu_wake_balance); goto out_set_cpu; } }
@@ -1134,10 +1141,8 @@ static int try_to_wake_up(task_t * p, un new_cpu = cpu;/* Could not wake to this_cpu. Wake to cpu instead */ out_set_cpu: -schedstat_inc (rq, ttwu_attempts); new_cpu =wake_idle (new_cpu, p);if (new_cpu != cpu &&cpu_isset (new_cpu, p->cpus_allowed)) { -schedstat_inc (rq, ttwu_moved);set_task_cpu (p, new_cpu);task_rq_unlock (rq, &flags);/* might preempt at this point */
@@ -1282,8 +1287,6 @@ void fastcall wake_up_new_task(task_t * this_cpu =smp_processor_id (); cpu =task_cpu (p); -schedstat_inc (rq, wunt_cnt); - array = rq->active;if (unlikely (p->used_slice ==-1 )) { p->used_slice =0 ;
@@ -1329,8 +1332,6 @@ void fastcall wake_up_new_task(task_t *__activate_task (p, rq, array);if (TASK_PREEMPTS_CURR (p, rq))resched_task (rq->curr); - -schedstat_inc (rq, wunt_moved);#endif }task_rq_unlock (rq, &flags);
@@ -1582,7 +1583,6 @@ static void sched_migrate_task(task_t *p || unlikely(cpu_is_offline(dest_cpu))) goto out; -schedstat_inc (rq, smt_cnt);/* force the process onto the specified CPU */ if (migrate_task (p, dest_cpu, &req)) {/* Need to wait for migration thread (might exit: take ref). */
@@ -1610,7 +1610,6 @@ void sched_exec(void)struct sched_domain *tmp, *sd =NULL ;int new_cpu, this_cpu =get_cpu (); -schedstat_inc (this_rq (), sbe_cnt);/* Prefer the current CPU if there's only this task running */ if (this_rq ()->nr_running <=1 ) goto out;
@@ -1752,13 +1751,10 @@ skip_queue: goto skip_bitmap; } -/* -* Right now, this is the only place pull_task() is called, -* so we can safely collect pull_task() stats here rather than -* inside pull_task(). -*/ -schedstat_inc (this_rq, pt_gained[idle]); -schedstat_inc (busiest, pt_lost[idle]); +#ifdef CONFIG_SCHEDSTATS +if (task_hot (tmp, busiest->timestamp_last_tick, sd)) +schedstat_inc (sd, lb_hot_pulled[idle]); +#endif pull_task (busiest, array, tmp, this_rq, dst_array, this_cpu); pulled++;
@@ -1771,6 +1767,15 @@ skip_queue: goto skip_bitmap; } out: +/* +* Right now, this is the only place pull_task() is called, +* so we can safely collect pull_task() stats here rather than +* inside pull_task(). +*/ +schedstat_add (this_rq, pt_gained[idle], pulled); +schedstat_add (busiest, pt_lost[idle], pulled); +schedstat_add (sd, lb_pulled[idle], pulled); +return pulled; }
@@ -2025,6 +2030,8 @@ static int load_balance(int this_cpu, rureturn nr_moved; out_balanced: +schedstat_inc (sd, lb_balanced[idle]); +/* tune up the balancing interval */ if (sd->balance_interval < sd->max_interval) sd->balance_interval *=2 ;
@@ -2066,8 +2073,11 @@ static int load_balance_newidle(int thisschedstat_add (sd, lb_imbalance[NEWLY_IDLE ], imbalance); nr_moved =move_tasks (this_rq, this_cpu, busiest, imbalance, sd,NEWLY_IDLE ); -if (!nr_moved) +if (!nr_moved) {schedstat_inc (sd, lb_failed[NEWLY_IDLE ]); + }else { +schedstat_inc (sd, lb_balanced[NEWLY_IDLE ]); + }spin_unlock (&busiest->lock);
@@ -2107,7 +2117,6 @@ static void active_load_balance(runqueuestruct sched_group *group, *busy_group;int i; -schedstat_inc (busiest, alb_cnt);if (busiest->nr_running <=1 )return ;
@@ -2117,6 +2126,8 @@ static void active_load_balance(runqueueif (!sd)return ; +schedstat_inc (sd, alb_cnt); + group = sd->groups;while (!cpu_isset (busiest_cpu, group->cpumask)) group = group->next;
@@ -2153,10 +2164,9 @@ static void active_load_balance(runqueue goto next_group;double_lock_balance (busiest, rq);if (move_tasks (rq, push_cpu, busiest,1 , sd,IDLE )) { -schedstat_inc (busiest, alb_lost); -schedstat_inc (rq, alb_gained); +schedstat_inc (sd, alb_pushed); }else { -schedstat_inc (busiest, alb_failed); +schedstat_inc (sd, alb_failed); }spin_unlock (&rq->lock); next_group:
@@ -2567,8 +2577,7 @@ go_idle: rq->expired = array; rq->expired->min_prio =MAX_PRIO ; array = rq->active; - }else -schedstat_inc (rq, sched_noswitch); + } idx =sched_find_first_bit (array->bitmap); queue = array->queue + idx;
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Quoted 5 lines · Nick Piggin
Hi,
I have a patch here to provide more useful statistics for me. Basically it moves a lot more of the balancing information into the domains instead of the runqueue, where it is nearly useless on multi-domain setups (eg. SMT+SMP, SMP+NUMA).
Which kernel version it is against?
RJW
Signature · 3 lines
For a successful technology, reality must take precedence over public relations, for nature cannot be fooled. -- Richard P. Feynman
Quoted 11 lines · Rafael J. Wysocki
Quoted 5 lines · Nick Piggin
Hi,
I have a patch here to provide more useful statistics for me. Basically it moves a lot more of the balancing information into the domains instead of the runqueue, where it is nearly useless on multi-domain setups (eg. SMT+SMP, SMP+NUMA).Which kernel version it is against?
-mm3 ... oh yeah that has nicksched in it, sorry that would put a spanner in the works.
I'll redo it to suit 2.6 if Rick acks it - the main info he needs is still valid, that is the output format.
Thanks
Nick
I have a patch here to provide more useful statistics for me. Basically it moves a lot more of the balancing information into the domains instead of the runqueue, where it is nearly useless on multi-domain setups (eg. SMT+SMP, SMP+NUMA).
It requires a version number bump, but that isn't much of an issue because I think we're about the only two using it at the moment. But your tools will need a little bit of work.
What do you think?
The idea of moving some counters from runqueues to domains is fine in general, but I've some questions about a couple of specific changes in your patch.
It looks to me like there are some changes in try_to_wake_up() that
aren't schedstats related, although schedstats code is among some that is moved around. Is there some code there that should be broken out separately?
alb_cnt
by moving this, we won't get an accurate look at the number of times we called active_load_balance and returned immediately because nr_running had slipped to 0 or 1. how about we add another counter to count that too, and/or change the name of this one?
lb_balanced
are you sure lb_balanced[idle] can't be deduced from lb_cnt[idle] and lb_failed[idle]?
ttwu_attempts
ttwu_moved
removing these makes it harder to determine how successful try_to_wake_up() was at moving a process. What counters would I use to get this information if these were removed?
ttwu_remote
ttwu_wake_remote
so what's the one line description of what these count now?
smt_cnt
sbe_cnt
how might I see how often sched_migrate_task() and sched_exec() were called if these were deleted?
lb_pulled
Rather than add another counter here, would it be as effective to make pt_gained a domain counter? Looks like you're collecting the same information. pt_lost would have to remain a runqueue counter, though, since losing a task has nothing to do with a particular domain.
Rick
Quoted 11 lines · Rick Lindsley
I have a patch here to provide more useful statistics for me. Basically it moves a lot more of the balancing information into the domains instead of the runqueue, where it is nearly useless on multi-domain setups (eg. SMT+SMP, SMP+NUMA).
It requires a version number bump, but that isn't much of an issue because I think we're about the only two using it at the moment. But your tools will need a little bit of work.
What do you think?
Quoted 9 lines
The idea of moving some counters from runqueues to domains is fine in general, but I've some questions about a couple of specific changes in your patch.
It looks to me like there are some changes in
try_to_wake_up()that
aren't schedstats related, although schedstats code is among some that is moved around. Is there some code there that should be broken out separately?
There is, yes. I'll be sure to seperate it.
Quoted 7 lines
alb_cnt
by moving this, we won't get an accurate look at the number of times we calledactive_load_balanceand returned immediately becausenr_runninghad slipped to 0 or 1. how about we add another counter to count that too, and/or change the name of this one?
OK.
Quoted 4 lines
lb_balanced
are you sure lb_balanced[idle] can't be deduced from lb_cnt[idle] and lb_failed[idle]?
I don't think so, because you also have the success case, which is !balanced && !failed.
Quoted 6 lines
ttwu_attempts
ttwu_moved
removing these makes it harder to determine how successfultry_to_wake_up()was at moving a process. What counters would I use to get this information if these were removed?
ttwu_cnt in the rq stats, and ttwu_wake_affine / ttwu_wake_balance in the domain stats.
Quoted 4 lines
ttwu_remote
ttwu_wake_remote
so what's the one line description of what these count now?
ttwu_remote/ttwu_wake_remote are the number of times a runqueue has woken a remote task / a remote task within that domain, respectively. Regardless of whether or not it gets pulled onto the local CPU.
Quoted 5 lines
smt_cnt
sbe_cnt
how might I see how oftensched_migrate_task()andsched_exec()were called if these were deleted?
sbe_pushed should basically be the same as smt_cnt, barring rare races with the cpus_allowed mask. I guess sbe_cnt doesn't have to go.
Quoted 3 lines
lb_pulled
Rather than add another counter here, would it be as effective to makept_gaineda domain counter? Looks like you're collecting
Yeah removing the runqueue counters for these would be good.
Quoted 3 lines
the same information.
pt_lostwould have to remain a runqueue counter, though, since losing a task has nothing to do with a particular domain.
Whatever domain that the pulling CPU was in, is also a fair candidate for pt_lost. Remember, all the domains are per-CPU so any information you can get from a per-runqueue counter you can also get from a domain counter.
I'll make a few changes and give you another look. Thanks for the comments.