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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2012-09-28 20:27:49 +0800
committerFengguang Wu <fengguang.wu@intel.com>2012-09-28 20:27:49 +0800
commit2f60d628ffd042e65e0b1d3431fb3e38d6f7c1be (patch)
treeab0abd6f9936db1441382f862028a4c22b7239e1
parent0e2f2b23672055e1301c11509d5b8eda7b718d8e (diff)
CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug
The CPU hotplug callback related to writeback calls writeback_set_ratelimit() during every state change in the hotplug sequence. This is unnecessary since num_online_cpus() changes only once during the entire hotplug operation. So invoke the function only once per hotplug, thereby avoiding the unnecessary repetition of those costly calculations. Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
-rw-r--r--mm/page-writeback.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 5ad5ce23c1e0..830893b2b3c7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1602,10 +1602,18 @@ void writeback_set_ratelimit(void)
}
static int __cpuinit
-ratelimit_handler(struct notifier_block *self, unsigned long u, void *v)
+ratelimit_handler(struct notifier_block *self, unsigned long action,
+ void *hcpu)
{
- writeback_set_ratelimit();
- return NOTIFY_DONE;
+
+ switch (action & ~CPU_TASKS_FROZEN) {
+ case CPU_ONLINE:
+ case CPU_DEAD:
+ writeback_set_ratelimit();
+ return NOTIFY_OK;
+ default:
+ return NOTIFY_DONE;
+ }
}
static struct notifier_block __cpuinitdata ratelimit_nb = {