[Devel] Re: [RFC 5/7] use percpu_counters for res_counter usage

[Glauber Costa]

On 03/30/2012 11:58 AM, KAMEZAWA Hiroyuki wrote:
> ==
> 
> Now, we do consume 'reserved' usage, we can avoid css_get(), an heavy atomic
> ops. You may need to move this code as
> 
> 	rcu_read_lock()
> 	....
> 	res_counter_charge()
> 	if (failure) {
> 		css_tryget()
> 		rcu_read_unlock()
> 	} else {
> 		rcu_read_unlock()
> 		return success;
> 	}
> 
> to compare performance. This css_get() affects performance very very much.

thanks for the tip.

But one thing:

To be sure: it effectively mean that we are drawing from a dead memcg
(because we pre-allocated, right?