On Thu, 21 Jul 2011 09:50:00 +0200 Michal Hocko <mhocko@xxxxxxx> wrote: > Currently we have two ways how to drain per-CPU caches for charges. > drain_all_stock_sync will synchronously drain all caches while > drain_all_stock_async will asynchronously drain only those that refer to > a given memory cgroup or its subtree in hierarchy. > Targeted async draining has been introduced by 26fe6168 (memcg: fix > percpu cached charge draining frequency) to reduce the cpu workers > number. > > sync draining is currently triggered only from mem_cgroup_force_empty > which is triggered only by userspace (mem_cgroup_force_empty_write) or > when a cgroup is removed (mem_cgroup_pre_destroy). Although these are > not usually frequent operations it still makes some sense to do targeted > draining as well, especially if the box has many CPUs. > > This patch unifies both methods to use the single code (drain_all_stock) > which relies on the original async implementation and just adds > flush_work to wait on all caches that are still under work for the sync > mode. > We are using FLUSHING_CACHED_CHARGE bit check to prevent from waiting on > a work that we haven't triggered. > Please note that both sync and async functions are currently protected > by percpu_charge_mutex so we cannot race with other drainers. > > Signed-off-by: Michal Hocko <mhocko@xxxxxxx> hmm..maybe good. Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>