Messages in this thread | | | Subject | Re: [PATCH] Revert "sched/fair: Fix O(nr_cgroups) in the load balancing path" | From | Srinivas Pandruvada <> | Date | Tue, 29 Oct 2019 12:59:49 -0700 |
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On Tue, 2019-10-29 at 12:34 -0700, Srinivas Pandruvada wrote: > On Fri, 2019-10-25 at 08:55 -0700, Doug Smythies wrote: > > [...] > > > Experiment method: > > > > enable only idle state 1 > > Dountil stopped > > apply a 100% load (all CPUs) > > after awhile (about 50 seconds) remove the load. > > allow a short transient delay (1 second). > > measure the processor package joules used over the next 149 > > seconds. > > Enduntil > > > > Kernel k5.4-rc2 + reversion (this method) > > Average processor package power: 9.148 watts (128 samples, > 7 > > hours) > > Minimum: 9.02 watts > > Maximum: 9.29 watts > > Note: outlyer data point group removed, as it was assumed the > > computer > > had something to do and wasn't actually "idle". > > > > Kernel 5.4-rc2: > > Average processor package power: 9.969 watts (150 samples, > 8 > > hours) > > Or 9% more energy for the idle phases of the work load. > > Minimum: 9.15 watts > > Maximum: 13.79 watts (51% more power) > > Hi Doug, > > Do you have intel_pstate_tracer output? I guess that when started > request to measure the measure joules, it started at higher P-state > without revert. > Other way is check by fixing the max and min scaling frequency to > some > frequency, then we shouldn't see power difference. I mean not significant power difference. Also to get real numbers, need to use some power meter measuring CPU power. If I can get your script, I may be able to measure that.
Thanks, Srinivas
> > Thanks, > Srinivas > > > > > > --- > > kernel/sched/fair.c | 43 +++++++++------------------------------ > > ---- > > 1 file changed, 9 insertions(+), 34 deletions(-) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 83ab35e..51625b8 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -381,10 +381,9 @@ static inline void > > assert_list_leaf_cfs_rq(struct rq *rq) > > SCHED_WARN_ON(rq->tmp_alone_branch != &rq->leaf_cfs_rq_list); > > } > > > > -/* Iterate thr' all leaf cfs_rq's on a runqueue */ > > -#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) > > \ > > - list_for_each_entry_safe(cfs_rq, pos, &rq->leaf_cfs_rq_list, > > \ > > - leaf_cfs_rq_list) > > +/* Iterate through all cfs_rq's on a runqueue in bottom-up order > > */ > > +#define for_each_leaf_cfs_rq(rq, cfs_rq) \ > > + list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, > > leaf_cfs_rq_list) > > > > /* Do the two (enqueued) entities belong to the same group ? */ > > static inline struct cfs_rq * > > @@ -481,8 +480,8 @@ static inline void > > assert_list_leaf_cfs_rq(struct > > rq *rq) > > { > > } > > > > -#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) \ > > - for (cfs_rq = &rq->cfs, pos = NULL; cfs_rq; cfs_rq = > > pos) > > +#define for_each_leaf_cfs_rq(rq, cfs_rq) \ > > + for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) > > > > static inline struct sched_entity *parent_entity(struct > > sched_entity > > *se) > > { > > @@ -7502,27 +7501,10 @@ static inline void > > update_blocked_load_status(struct rq *rq, bool has_blocked) { > > > > #ifdef CONFIG_FAIR_GROUP_SCHED > > > > -static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) > > -{ > > - if (cfs_rq->load.weight) > > - return false; > > - > > - if (cfs_rq->avg.load_sum) > > - return false; > > - > > - if (cfs_rq->avg.util_sum) > > - return false; > > - > > - if (cfs_rq->avg.runnable_load_sum) > > - return false; > > - > > - return true; > > -} > > - > > static void update_blocked_averages(int cpu) > > { > > struct rq *rq = cpu_rq(cpu); > > - struct cfs_rq *cfs_rq, *pos; > > + struct cfs_rq *cfs_rq; > > const struct sched_class *curr_class; > > struct rq_flags rf; > > bool done = true; > > @@ -7534,7 +7516,7 @@ static void update_blocked_averages(int cpu) > > * Iterates the task_group tree in a bottom up fashion, see > > * list_add_leaf_cfs_rq() for details. > > */ > > - for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) { > > + for_each_leaf_cfs_rq(rq, cfs_rq) { > > struct sched_entity *se; > > > > if (update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), > > cfs_rq)) > > @@ -7545,13 +7527,6 @@ static void update_blocked_averages(int cpu) > > if (se && !skip_blocked_update(se)) > > update_load_avg(cfs_rq_of(se), se, 0); > > > > - /* > > - * There can be a lot of idle CPU cgroups. Don't let > > fully > > - * decayed cfs_rqs linger on the list. > > - */ > > - if (cfs_rq_is_decayed(cfs_rq)) > > - list_del_leaf_cfs_rq(cfs_rq); > > - > > /* Don't need periodic decay once load/util_avg are > > null */ > > if (cfs_rq_has_blocked(cfs_rq)) > > done = false; > > @@ -10444,10 +10419,10 @@ const struct sched_class fair_sched_class > > = > > { > > #ifdef CONFIG_SCHED_DEBUG > > void print_cfs_stats(struct seq_file *m, int cpu) > > { > > - struct cfs_rq *cfs_rq, *pos; > > + struct cfs_rq *cfs_rq; > > > > rcu_read_lock(); > > - for_each_leaf_cfs_rq_safe(cpu_rq(cpu), cfs_rq, pos) > > + for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) > > print_cfs_rq(m, cpu, cfs_rq); > > rcu_read_unlock(); > > } > >
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