From: Srivatsa S. Bhat <[email protected]> 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 <[email protected]> --- mm/page-writeback.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 5ad5ce2..830893b 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 = { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
