On Thu, Feb 25, 2016 at 04:55:26PM +0000, Mathieu Desnoyers wrote: > ----- On Feb 25, 2016, at 4:56 AM, Peter Zijlstra peterz@xxxxxxxxxxxxx wrote: > The restartable sequences are intrinsically designed to work > on per-cpu data, so they need to fetch the current CPU number > within the rseq critical section. This is where the getcpu_cache > system call becomes very useful when combined with rseq: > getcpu_cache allows reading the current CPU number in a > fraction of cycle. Yes yes, I know how restartable sequences work. But what I worry about is that they want a cpu number and a sequence number, and for performance it would be very good if those live in the same cacheline. That means either getcpu needs to grow a seq number, or restartable sequences need to _also_ provide the cpu number. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
