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[PATCH] sched: add option to serialize load balancing

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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>
This commit is contained in:
Christoph Lameter 2006-12-10 02:20:29 -08:00 committed by Linus Torvalds
parent 1bd77f2da5
commit 08c183f31b
7 changed files with 16 additions and 1 deletions
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1
include/asm-i386/topology.h
View file

@ -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, \

1
include/asm-ia64/topology.h
View file

@ -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, \

1
include/asm-powerpc/topology.h
View file

@ -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, \

1
include/asm-x86_64/topology.h
View file

@ -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, \

1
include/linux/sched.h
View file

@ -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)

3
include/linux/topology.h
View file

@ -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, \

9
kernel/sched.c
View file

@ -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;
}