[PATCH] cpuset semaphore depth check optimize
Optimize the deadlock avoidance check on the global cpuset semaphore cpuset_sem. Instead of adding a depth counter to the task struct of each task, rather just two words are enough, one to store the depth and the other the current cpuset_sem holder. Thanks to Nikita Danilov for the idea. Signed-off-by: Paul Jackson <pj@sgi.com> [ We may want to change this further, but at least it's now a totally internal decision to the cpusets code ] Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -785,7 +785,6 @@ struct task_struct {
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short il_next;
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short il_next;
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#endif
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#endif
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#ifdef CONFIG_CPUSETS
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#ifdef CONFIG_CPUSETS
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short cpuset_sem_nest_depth;
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struct cpuset *cpuset;
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struct cpuset *cpuset;
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nodemask_t mems_allowed;
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nodemask_t mems_allowed;
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int cpuset_mems_generation;
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int cpuset_mems_generation;
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@ -180,6 +180,8 @@ static struct super_block *cpuset_sb = NULL;
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*/
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*/
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static DECLARE_MUTEX(cpuset_sem);
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static DECLARE_MUTEX(cpuset_sem);
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static struct task_struct *cpuset_sem_owner;
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static int cpuset_sem_depth;
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/*
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/*
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* The global cpuset semaphore cpuset_sem can be needed by the
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* The global cpuset semaphore cpuset_sem can be needed by the
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@ -200,16 +202,19 @@ static DECLARE_MUTEX(cpuset_sem);
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static inline void cpuset_down(struct semaphore *psem)
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static inline void cpuset_down(struct semaphore *psem)
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{
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{
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if (current->cpuset_sem_nest_depth == 0)
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if (cpuset_sem_owner != current) {
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down(psem);
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down(psem);
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current->cpuset_sem_nest_depth++;
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cpuset_sem_owner = current;
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}
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cpuset_sem_depth++;
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}
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}
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static inline void cpuset_up(struct semaphore *psem)
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static inline void cpuset_up(struct semaphore *psem)
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{
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{
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current->cpuset_sem_nest_depth--;
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if (--cpuset_sem_depth == 0) {
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if (current->cpuset_sem_nest_depth == 0)
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cpuset_sem_owner = NULL;
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up(psem);
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up(psem);
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}
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}
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}
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/*
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/*
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