On Mon, 16 Mar 2020 13:32:41 -0700 "Paul E. McKenney" <paulmck@xxxxxxxxxx> wrote: > > Just curious, why is the "rude" version better than SRCU? Seems the > > schedule_on_each_cpu() would be much slower than SRCU especially if > > there are 1000s of CPUs involved. Is there any reason that is a better > > alternative? > > The rude version has much faster readers, and the story I hear is that > there are not expected to be all that many concurrent updaters. > > But to get more detail, why not ask Steven why he chose not to use SRCU? > (I know the story for the BPF guys, and it is because of SRCU's read-side > overhead.) Same for the function side (if not even more so). This would require adding a srcu_read_lock() to all functions that can be traced! That would be a huge kill in performance. Probably to the point no one would bother even using function tracer. -- Steve
