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authorPaul Jackson <pj@sgi.com>2005-09-12 04:30:30 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-12 09:16:27 -0700
commitb3426599af9524104be6938bcb1fcaab314781c7 (patch)
treec6d354bddb5b8cd298d139b60a9257ebd8323b90 /kernel
parentf24ec7f6c6278c0ea4c00efe96d50b1e66796c44 (diff)
[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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cpuset.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 407b5f0a8c8e..79866bc6b3a1 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -180,6 +180,8 @@ static struct super_block *cpuset_sb = NULL;
*/
static DECLARE_MUTEX(cpuset_sem);
+static struct task_struct *cpuset_sem_owner;
+static int cpuset_sem_depth;
/*
* The global cpuset semaphore cpuset_sem can be needed by the
@@ -200,16 +202,19 @@ static DECLARE_MUTEX(cpuset_sem);
static inline void cpuset_down(struct semaphore *psem)
{
- if (current->cpuset_sem_nest_depth == 0)
+ if (cpuset_sem_owner != current) {
down(psem);
- current->cpuset_sem_nest_depth++;
+ cpuset_sem_owner = current;
+ }
+ cpuset_sem_depth++;
}
static inline void cpuset_up(struct semaphore *psem)
{
- current->cpuset_sem_nest_depth--;
- if (current->cpuset_sem_nest_depth == 0)
+ if (--cpuset_sem_depth == 0) {
+ cpuset_sem_owner = NULL;
up(psem);
+ }
}
/*

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