Messages in this thread | | | Date | Tue, 13 Oct 2009 11:20:57 -0400 (EDT) | From | Christoph Lameter <> | Subject | Re: [this_cpu_xx V6 3/7] Use this_cpu operations in slub |
| |
On Tue, 13 Oct 2009, Tejun Heo wrote:
> Yeah, widespread use of underscored versions isn't very desirable. > The underscored versions should notify certain specific exceptional > conditions instead of being used as general optimization (which > doesn't make much sense after all as the optimization is only > meaningful with debug option turned on). Are you interested in doing > a sweeping patch to drop underscores from __this_cpu_*() conversions?
Nope. __this_cpu_add/dec cannot be converted.
__this_cpu_ptr could be converted to this_cpu_ptr but I think the __ are useful there too to show that we are in a preempt section.
The calls to raw_smp_processor_id and smp_processor_id() are only useful in the fallback case. There is no need for those if the arch has a way to provide the current percpu offset. So we in effect have two meanings of __ right now.
1. We do not care about the preempt state (thus we call raw_smp_processor_id so that the preempt state does not trigger)
2. We do not need to disable preempt before the operation.
__this_cpu_ptr only implies 1. __this_cpu_add uses 1 and 2.
| |