sched: Optimize the !power_savings_balance during fbg()
Impact: cleanup, micro-optimization We don't need to perform power_savings balance if either the cpu is NOT_IDLE or if the sched_domain doesn't contain the SD_POWERSAVINGS_BALANCE flag set. Currently, we check for these conditions multiple number of times, even though these variables don't change over the scope of find_busiest_group(). Check once, and store the value in the already exiting "power_savings_balance" variable. Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: "Balbir Singh" <balbir@in.ibm.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com> Cc: Bharata B Rao <bharata@linux.vnet.ibm.com> Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com> LKML-Reference: <20090325091417.13992.2657.stgit@sofia.in.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -3386,8 +3386,17 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
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int load_idx;
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#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
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sds->power_savings_balance = 1;
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sds->min_nr_running = ULONG_MAX;
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/*
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* Busy processors will not participate in power savings
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* balance.
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*/
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if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
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sds->power_savings_balance = 0;
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else {
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sds->power_savings_balance = 1;
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sds->min_nr_running = ULONG_MAX;
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sds->leader_nr_running = 0;
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}
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#endif
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load_idx = get_sd_load_idx(sd, idle);
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@ -3422,12 +3431,8 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
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}
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#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
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/*
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* Busy processors will not participate in power savings
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* balance.
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*/
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if (idle == CPU_NOT_IDLE ||
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!(sd->flags & SD_POWERSAVINGS_BALANCE))
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if (!sds->power_savings_balance)
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goto group_next;
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/*
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@ -3651,7 +3656,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
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out_balanced:
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#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
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if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
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if (!sds.power_savings_balance)
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goto ret;
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if (sds.this != sds.group_leader || sds.group_leader == sds.group_min)
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