On Thu, 15 Jan 2015, Steven Rostedt wrote: > profiling function tracing I discovered that accessing preempt_count > was actually quite expensive, even just to read. But it may not be as > bad since Peter Zijlstra converted preempt_count to a per_cpu variable. > Although, IIRC, the perf profiling showed the access to the %gs > register was where the time consuming was happening, which is what > I believe per_cpu variables still use. The %gs register is not used since the address of the per cpu area is available as one of the first fields in the per cpu areas. -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>