On Wed, 2011-03-30 at 09:06 +0800, Andrew Morton wrote: > On Wed, 30 Mar 2011 09:01:22 +0800 Shaohua Li <shaohua.li@xxxxxxxxx> wrote: > > > +/* > > + * Make sure vm_committed_as in one cacheline and not cacheline shared with > > + * other variables. It can be updated by several CPUs frequently. > > + */ > > +struct percpu_counter vm_committed_as ____cacheline_internodealigned_in_smp; > > The mystery deepens. The only cross-cpu writeable fields in there are > percpu_counter.lock and its companion percpu_counter.count. If CPUs > are contending for the lock then that itself is a problem - how does > adding some padding to the struct help anything? I had another patch trying to address the lock contention (for case OVERCOMMIT_GUESS), will send out soon. But thought better to have the correct alignment for OVERCOMMIT_NEVER case. Thanks, Shaohua -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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>