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sched: Add SD_PREFER_LOCAL

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And turn it on for NUMA and MC domains. This improves
locality in balancing decisions by keeping up to
capacity amount of tasks local before looking for idle
CPUs. (and twice the capacity if SD_POWERSAVINGS_BALANCE
is set.)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-09-16 08:28:30 +02:00 committed by Ingo Molnar
parent e69b0f1b41
commit 59abf02644
3 changed files with 8 additions and 3 deletions
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2
include/linux/sched.h
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@ -805,7 +805,7 @@ enum cpu_idle_type {
#define SD_BALANCE_FORK 0x0008 /* Balance on fork, clone */
#define SD_BALANCE_WAKE 0x0010 /* Balance on wakeup */
#define SD_WAKE_AFFINE 0x0020 /* Wake task to waking CPU */
#define SD_PREFER_LOCAL 0x0040 /* Prefer to keep tasks local to this domain */
#define SD_SHARE_CPUPOWER 0x0080 /* Domain members share cpu power */
#define SD_POWERSAVINGS_BALANCE 0x0100 /* Balance for power savings */
#define SD_SHARE_PKG_RESOURCES 0x0200 /* Domain members share cpu pkg resources */

2
include/linux/topology.h
View file

@ -129,6 +129,7 @@ int arch_update_cpu_topology(void);
| 1*SD_BALANCE_FORK \
| 1*SD_BALANCE_WAKE \
| 1*SD_WAKE_AFFINE \
| 1*SD_PREFER_LOCAL \
| 0*SD_SHARE_CPUPOWER \
| 1*SD_SHARE_PKG_RESOURCES \
| 0*SD_SERIALIZE \
@ -161,6 +162,7 @@ int arch_update_cpu_topology(void);
| 1*SD_BALANCE_FORK \
| 1*SD_BALANCE_WAKE \
| 1*SD_WAKE_AFFINE \
| 1*SD_PREFER_LOCAL \
| 0*SD_SHARE_CPUPOWER \
| 0*SD_SHARE_PKG_RESOURCES \
| 0*SD_SERIALIZE \

7
kernel/sched_fair.c
View file

@ -1360,7 +1360,7 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int flags)
* If power savings logic is enabled for a domain, see if we
* are not overloaded, if so, don't balance wider.
*/
if (tmp->flags & SD_POWERSAVINGS_BALANCE) {
if (tmp->flags & (SD_POWERSAVINGS_BALANCE|SD_PREFER_LOCAL)) {
unsigned long power = 0;
unsigned long nr_running = 0;
unsigned long capacity;
@ -1373,7 +1373,10 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int flags)
capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
if (nr_running/2 < capacity)
if (tmp->flags & SD_POWERSAVINGS_BALANCE)
nr_running /= 2;
if (nr_running < capacity)
break;
}