Re: [PATCH] CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug

2012-10-03 Thread Ni zhan Chen 

On 09/28/2012 08:27 PM, Fengguang Wu wrote:

On Tue, Sep 25, 2012 at 02:18:20AM +0530, Srivatsa S. Bhat wrote:

From: Srivatsa S. Bhat 

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 
---

Looks good to me. I'll include it in the writeback tree.


Hi Fengguang,

Could you tell me when  inode->i_state & I_DIRTY will be set? thanks.

Regards,
Chen



Thanks,
Fengguang

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Re: [PATCH] CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug

2012-09-28 Thread Srivatsa S. Bhat 
On 09/28/2012 05:57 PM, Fengguang Wu wrote:
> On Tue, Sep 25, 2012 at 02:18:20AM +0530, Srivatsa S. Bhat wrote:
>>
>> From: Srivatsa S. Bhat 
>>
>> 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 
>> ---
> 
> Looks good to me. I'll include it in the writeback tree.
> 

Great, thanks!
 
Regards,
Srivatsa S. Bhat

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Re: [PATCH] CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug

2012-09-28 Thread Fengguang Wu 
On Tue, Sep 25, 2012 at 02:18:20AM +0530, Srivatsa S. Bhat wrote:
> 
> From: Srivatsa S. Bhat 
> 
> 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 
> ---

Looks good to me. I'll include it in the writeback tree.

Thanks,
Fengguang
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[PATCH] CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug

2012-09-24 Thread Srivatsa S. Bhat 

From: Srivatsa S. Bhat 

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 
---

 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 = {


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