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authorSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>2008-01-25 15:08:00 -0500
committerIngo Molnar <mingo@elte.hu>2008-01-25 15:08:00 -0500
commita183561567b5446d3362b4839bd4f744f4b2af1e (patch)
tree7bfa46fd0bf4a96e96500732d188f1ef4b04454d
parent58e2d4ca581167c2a079f4ee02be2f0bc52e8729 (diff)
sched: introduce a mutex and corresponding API to serialize access to doms_curarray
doms_cur[] array represents various scheduling domains which are mutually exclusive. Currently cpusets code can modify this array (by calling partition_sched_domains()) as a result of user modifying sched_load_balance flag for various cpusets. This patch introduces a mutex and corresponding API (only when CONFIG_FAIR_GROUP_SCHED is defined) which allows a reader to safely read the doms_cur[] array w/o worrying abt concurrent modifications to the array. The fair group scheduler code (introduced in next patch of this series) makes use of this mutex to walk thr' doms_cur[] array while rebalancing shares of task groups across cpus. Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index c915f3e6e593..d9585f15043f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -185,6 +185,9 @@ static struct cfs_rq *init_cfs_rq_p[NR_CPUS];
185 */ 185 */
186static DEFINE_MUTEX(task_group_mutex); 186static DEFINE_MUTEX(task_group_mutex);
187 187
188/* doms_cur_mutex serializes access to doms_cur[] array */
189static DEFINE_MUTEX(doms_cur_mutex);
190
188/* Default task group. 191/* Default task group.
189 * Every task in system belong to this group at bootup. 192 * Every task in system belong to this group at bootup.
190 */ 193 */
@@ -234,11 +237,23 @@ static inline void unlock_task_group_list(void)
234 mutex_unlock(&task_group_mutex); 237 mutex_unlock(&task_group_mutex);
235} 238}
236 239
240static inline void lock_doms_cur(void)
241{
242 mutex_lock(&doms_cur_mutex);
243}
244
245static inline void unlock_doms_cur(void)
246{
247 mutex_unlock(&doms_cur_mutex);
248}
249
237#else 250#else
238 251
239static inline void set_task_cfs_rq(struct task_struct *p, unsigned int cpu) { } 252static inline void set_task_cfs_rq(struct task_struct *p, unsigned int cpu) { }
240static inline void lock_task_group_list(void) { } 253static inline void lock_task_group_list(void) { }
241static inline void unlock_task_group_list(void) { } 254static inline void unlock_task_group_list(void) { }
255static inline void lock_doms_cur(void) { }
256static inline void unlock_doms_cur(void) { }
242 257
243#endif /* CONFIG_FAIR_GROUP_SCHED */ 258#endif /* CONFIG_FAIR_GROUP_SCHED */
244 259
@@ -6543,6 +6558,8 @@ void partition_sched_domains(int ndoms_new, cpumask_t *doms_new)
6543{ 6558{
6544 int i, j; 6559 int i, j;
6545 6560
6561 lock_doms_cur();
6562
6546 /* always unregister in case we don't destroy any domains */ 6563 /* always unregister in case we don't destroy any domains */
6547 unregister_sched_domain_sysctl(); 6564 unregister_sched_domain_sysctl();
6548 6565
@@ -6583,6 +6600,8 @@ match2:
6583 ndoms_cur = ndoms_new; 6600 ndoms_cur = ndoms_new;
6584 6601
6585 register_sched_domain_sysctl(); 6602 register_sched_domain_sysctl();
6603
6604 unlock_doms_cur();
6586} 6605}
6587 6606
6588#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) 6607#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)