[PATCH] sched: add option to serialize load balancing
Large sched domains can be very expensive to scan. Add an option SD_SERIALIZE to the sched domain flags. If that flag is set then we make sure that no other such domain is being balanced. [akpm@osdl.org: build fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Peter Williams <pwil3058@bigpond.net.au> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <clameter@sgi.com> Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com> Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -89,6 +89,7 @@ static inline int node_to_first_cpu(int node)
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.flags = SD_LOAD_BALANCE \
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| SD_BALANCE_EXEC \
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| SD_BALANCE_FORK \
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| SD_SERIALIZE \
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| SD_WAKE_BALANCE, \
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.last_balance = jiffies, \
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.balance_interval = 1, \
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@ -101,6 +101,7 @@ void build_cpu_to_node_map(void);
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.flags = SD_LOAD_BALANCE \
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| SD_BALANCE_EXEC \
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| SD_BALANCE_FORK \
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| SD_SERIALIZE \
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| SD_WAKE_BALANCE, \
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.last_balance = jiffies, \
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.balance_interval = 64, \
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@ -66,6 +66,7 @@ static inline int pcibus_to_node(struct pci_bus *bus)
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| SD_BALANCE_EXEC \
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| SD_BALANCE_NEWIDLE \
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| SD_WAKE_IDLE \
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| SD_SERIALIZE \
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| SD_WAKE_BALANCE, \
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.last_balance = jiffies, \
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.balance_interval = 1, \
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@ -47,6 +47,7 @@ extern int __node_distance(int, int);
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.flags = SD_LOAD_BALANCE \
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| SD_BALANCE_FORK \
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| SD_BALANCE_EXEC \
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| SD_SERIALIZE \
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| SD_WAKE_BALANCE, \
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.last_balance = jiffies, \
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.balance_interval = 1, \
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@ -648,6 +648,7 @@ enum idle_type
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#define SD_SHARE_CPUPOWER 128 /* Domain members share cpu power */
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#define SD_POWERSAVINGS_BALANCE 256 /* Balance for power savings */
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#define SD_SHARE_PKG_RESOURCES 512 /* Domain members share cpu pkg resources */
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#define SD_SERIALIZE 1024 /* Only a single load balancing instance */
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#define BALANCE_FOR_MC_POWER \
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(sched_smt_power_savings ? SD_POWERSAVINGS_BALANCE : 0)
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@ -194,7 +194,8 @@
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.wake_idx = 0, /* unused */ \
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.forkexec_idx = 0, /* unused */ \
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.per_cpu_gain = 100, \
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.flags = SD_LOAD_BALANCE, \
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.flags = SD_LOAD_BALANCE \
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| SD_SERIALIZE, \
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.last_balance = jiffies, \
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.balance_interval = 64, \
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.nr_balance_failed = 0, \
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@ -2880,6 +2880,7 @@ static void update_load(struct rq *this_rq)
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*
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* Balancing parameters are set up in arch_init_sched_domains.
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*/
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static DEFINE_SPINLOCK(balancing);
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static void run_rebalance_domains(struct softirq_action *h)
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{
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@ -2909,6 +2910,11 @@ static void run_rebalance_domains(struct softirq_action *h)
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if (unlikely(!interval))
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interval = 1;
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if (sd->flags & SD_SERIALIZE) {
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if (!spin_trylock(&balancing))
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goto out;
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}
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if (time_after_eq(jiffies, sd->last_balance + interval)) {
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if (load_balance(this_cpu, this_rq, sd, idle)) {
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/*
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@ -2920,6 +2926,9 @@ static void run_rebalance_domains(struct softirq_action *h)
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}
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sd->last_balance = jiffies;
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}
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if (sd->flags & SD_SERIALIZE)
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spin_unlock(&balancing);
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out:
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if (time_after(next_balance, sd->last_balance + interval))
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next_balance = sd->last_balance + interval;
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}
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