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author | Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> | 2008-01-25 21:08:00 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-01-25 21:08:00 +0100 |
commit | a183561567b5446d3362b4839bd4f744f4b2af1e (patch) | |
tree | 7bfa46fd0bf4a96e96500732d188f1ef4b04454d /kernel/sched.c | |
parent | 58e2d4ca581167c2a079f4ee02be2f0bc52e8729 (diff) | |
download | op-kernel-dev-a183561567b5446d3362b4839bd4f744f4b2af1e.zip op-kernel-dev-a183561567b5446d3362b4839bd4f744f4b2af1e.tar.gz |
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>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r-- | kernel/sched.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index c915f3e..d9585f1 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -185,6 +185,9 @@ static struct cfs_rq *init_cfs_rq_p[NR_CPUS]; */ static DEFINE_MUTEX(task_group_mutex); +/* doms_cur_mutex serializes access to doms_cur[] array */ +static DEFINE_MUTEX(doms_cur_mutex); + /* Default task group. * Every task in system belong to this group at bootup. */ @@ -234,11 +237,23 @@ static inline void unlock_task_group_list(void) mutex_unlock(&task_group_mutex); } +static inline void lock_doms_cur(void) +{ + mutex_lock(&doms_cur_mutex); +} + +static inline void unlock_doms_cur(void) +{ + mutex_unlock(&doms_cur_mutex); +} + #else static inline void set_task_cfs_rq(struct task_struct *p, unsigned int cpu) { } static inline void lock_task_group_list(void) { } static inline void unlock_task_group_list(void) { } +static inline void lock_doms_cur(void) { } +static inline void unlock_doms_cur(void) { } #endif /* CONFIG_FAIR_GROUP_SCHED */ @@ -6543,6 +6558,8 @@ void partition_sched_domains(int ndoms_new, cpumask_t *doms_new) { int i, j; + lock_doms_cur(); + /* always unregister in case we don't destroy any domains */ unregister_sched_domain_sysctl(); @@ -6583,6 +6600,8 @@ match2: ndoms_cur = ndoms_new; register_sched_domain_sysctl(); + + unlock_doms_cur(); } #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) |