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authorChristoph Lameter <clameter@sgi.com>2006-12-10 02:20:29 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-10 09:55:43 -0800
commit08c183f31bdbb709f177f6d3110d5f288ea33933 (patch)
treebe7b84c07f3b0bf29473bad2b7b788fa189f948e
parent1bd77f2da58e9cdd1f159217887343dadd9af417 (diff)
[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>
-rw-r--r--include/asm-i386/topology.h1
-rw-r--r--include/asm-ia64/topology.h1
-rw-r--r--include/asm-powerpc/topology.h1
-rw-r--r--include/asm-x86_64/topology.h1
-rw-r--r--include/linux/sched.h1
-rw-r--r--include/linux/topology.h3
-rw-r--r--kernel/sched.c9
7 files changed, 16 insertions, 1 deletions
diff --git a/include/asm-i386/topology.h b/include/asm-i386/topology.h
index 978d09596130..ac58580ad664 100644
--- a/include/asm-i386/topology.h
+++ b/include/asm-i386/topology.h
@@ -89,6 +89,7 @@ static inline int node_to_first_cpu(int node)
.flags = SD_LOAD_BALANCE \
| SD_BALANCE_EXEC \
| SD_BALANCE_FORK \
+ | SD_SERIALIZE \
| SD_WAKE_BALANCE, \
.last_balance = jiffies, \
.balance_interval = 1, \
diff --git a/include/asm-ia64/topology.h b/include/asm-ia64/topology.h
index a6e38565ab4c..22ed6749557e 100644
--- a/include/asm-ia64/topology.h
+++ b/include/asm-ia64/topology.h
@@ -101,6 +101,7 @@ void build_cpu_to_node_map(void);
.flags = SD_LOAD_BALANCE \
| SD_BALANCE_EXEC \
| SD_BALANCE_FORK \
+ | SD_SERIALIZE \
| SD_WAKE_BALANCE, \
.last_balance = jiffies, \
.balance_interval = 64, \
diff --git a/include/asm-powerpc/topology.h b/include/asm-powerpc/topology.h
index 50c014007de7..6610495f5f16 100644
--- a/include/asm-powerpc/topology.h
+++ b/include/asm-powerpc/topology.h
@@ -66,6 +66,7 @@ static inline int pcibus_to_node(struct pci_bus *bus)
| SD_BALANCE_EXEC \
| SD_BALANCE_NEWIDLE \
| SD_WAKE_IDLE \
+ | SD_SERIALIZE \
| SD_WAKE_BALANCE, \
.last_balance = jiffies, \
.balance_interval = 1, \
diff --git a/include/asm-x86_64/topology.h b/include/asm-x86_64/topology.h
index 5c8f49280dbc..2facec5914d2 100644
--- a/include/asm-x86_64/topology.h
+++ b/include/asm-x86_64/topology.h
@@ -47,6 +47,7 @@ extern int __node_distance(int, int);
.flags = SD_LOAD_BALANCE \
| SD_BALANCE_FORK \
| SD_BALANCE_EXEC \
+ | SD_SERIALIZE \
| SD_WAKE_BALANCE, \
.last_balance = jiffies, \
.balance_interval = 1, \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1208feab46e0..ea92e5c89089 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -648,6 +648,7 @@ enum idle_type
#define SD_SHARE_CPUPOWER 128 /* Domain members share cpu power */
#define SD_POWERSAVINGS_BALANCE 256 /* Balance for power savings */
#define SD_SHARE_PKG_RESOURCES 512 /* Domain members share cpu pkg resources */
+#define SD_SERIALIZE 1024 /* Only a single load balancing instance */
#define BALANCE_FOR_MC_POWER \
(sched_smt_power_savings ? SD_POWERSAVINGS_BALANCE : 0)
diff --git a/include/linux/topology.h b/include/linux/topology.h
index b93bb6cc6cc2..6c5a6e6e813b 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -194,7 +194,8 @@
.wake_idx = 0, /* unused */ \
.forkexec_idx = 0, /* unused */ \
.per_cpu_gain = 100, \
- .flags = SD_LOAD_BALANCE, \
+ .flags = SD_LOAD_BALANCE \
+ | SD_SERIALIZE, \
.last_balance = jiffies, \
.balance_interval = 64, \
.nr_balance_failed = 0, \
diff --git a/kernel/sched.c b/kernel/sched.c
index 0a4a26b21f69..2b2b780939c9 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2880,6 +2880,7 @@ static void update_load(struct rq *this_rq)
*
* Balancing parameters are set up in arch_init_sched_domains.
*/
+static DEFINE_SPINLOCK(balancing);
static void run_rebalance_domains(struct softirq_action *h)
{
@@ -2909,6 +2910,11 @@ static void run_rebalance_domains(struct softirq_action *h)
if (unlikely(!interval))
interval = 1;
+ if (sd->flags & SD_SERIALIZE) {
+ if (!spin_trylock(&balancing))
+ goto out;
+ }
+
if (time_after_eq(jiffies, sd->last_balance + interval)) {
if (load_balance(this_cpu, this_rq, sd, idle)) {
/*
@@ -2920,6 +2926,9 @@ static void run_rebalance_domains(struct softirq_action *h)
}
sd->last_balance = jiffies;
}
+ if (sd->flags & SD_SERIALIZE)
+ spin_unlock(&balancing);
+out:
if (time_after(next_balance, sd->last_balance + interval))
next_balance = sd->last_balance + interval;
}