Messages in this thread Patch in this message | | | From | Yuyang Du <> | Subject | [RFC PATCH 8/9 v4] Implement Workload Consolidation in nohz_idle_balance | Date | Wed, 25 Jun 2014 08:36:07 +0800 |
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In periodic nohz idle balance, we skip kicking idle but non-consolidated CPUs.
Signed-off-by: Yuyang Du <yuyang.du@intel.com> --- kernel/sched/fair.c | 55 +++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 45 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index bf65fde..549f6e0 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6983,10 +6983,45 @@ static struct { static inline int find_new_ilb(void) { - int ilb = cpumask_first(nohz.idle_cpus_mask); + int ilb; - if (ilb < nr_cpu_ids && idle_cpu(ilb)) - return ilb; + /* + * Optimize for the case when we have no idle CPUs or only one + * idle CPU. Don't walk the sched_domain hierarchy in such cases + */ + if (cpumask_weight(nohz.idle_cpus_mask) < 2) + return nr_cpu_ids; + + ilb = cpumask_first(nohz.idle_cpus_mask); + + if (ilb < nr_cpu_ids && idle_cpu(ilb)) { + struct sched_domain *sd; + int this_cpu = smp_processor_id(); + + sd = per_cpu(sd_wc, this_cpu); + if (sd) { + struct cpumask *nonshielded_cpus = __get_cpu_var(load_balance_mask); + + cpumask_copy(nonshielded_cpus, nohz.idle_cpus_mask); + + rcu_read_lock(); + wc_nonshielded_mask(this_cpu, sd, nonshielded_cpus); + rcu_read_unlock(); + + if (cpumask_weight(nonshielded_cpus) < 2) + return nr_cpu_ids; + + /* + * get idle load balancer again + */ + ilb = cpumask_first(nonshielded_cpus); + + if (ilb < nr_cpu_ids && idle_cpu(ilb)) + return ilb; + } + else + return ilb; + } return nr_cpu_ids; } @@ -7217,7 +7252,7 @@ out: * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the * rebalancing for all the cpus for whom scheduler ticks are stopped. */ -static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) +static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle, struct cpumask *mask) { int this_cpu = this_rq->cpu; struct rq *rq; @@ -7227,7 +7262,7 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu))) goto end; - for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { + for_each_cpu(balance_cpu, mask) { if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) continue; @@ -7280,10 +7315,10 @@ static inline int nohz_kick_needed(struct rq *rq) if (unlikely(rq->idle_balance)) return 0; - /* - * We may be recently in ticked or tickless idle mode. At the first - * busy tick after returning from idle, we will update the busy stats. - */ + /* + * We may be recently in ticked or tickless idle mode. At the first + * busy tick after returning from idle, we will update the busy stats. + */ set_cpu_sd_state_busy(); nohz_balance_exit_idle(cpu); @@ -7326,7 +7361,7 @@ need_kick: return 1; } #else -static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { } +static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle, struct cpumask *mask) { } #endif /* -- 1.7.9.5
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