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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
