On Wed, Aug 17, 2011 at 11:50:53PM -0700, Greg Thelen wrote: > Both mem_cgroup_charge_statistics() and mem_cgroup_move_account() were > unnecessarily disabling preemption when adjusting per-cpu counters: > preempt_disable() > __this_cpu_xxx() > __this_cpu_yyy() > preempt_enable() > > This change does not disable preemption and thus CPU switch is possible > within these routines. This does not cause a problem because the total > of all cpu counters is summed when reporting stats. Now both > mem_cgroup_charge_statistics() and mem_cgroup_move_account() look like: > this_cpu_xxx() > this_cpu_yyy() Note that on non-x86, these operations themselves actually disable and reenable preemption each time, so you trade a pair of add and sub on x86 - preempt_disable() __this_cpu_xxx() __this_cpu_yyy() - preempt_enable() with preempt_disable() __this_cpu_xxx() + preempt_enable() + preempt_disable() __this_cpu_yyy() preempt_enable() everywhere else. -- 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>