Try building without it and see what happens when you run the tests. Might well be that it is unnecessary, but I will defer to Mathieu on that point.
Thanx, Paul On Wed, Apr 27, 2016 at 10:18:04PM -0400, Yuxin Ren wrote: > As they don't currently perform grace period, why do we use the rcu_gp_lock? > > Thank you. > Yuxin > > On Wed, Apr 27, 2016 at 10:08 PM, Paul E. McKenney > <paul...@linux.vnet.ibm.com> wrote: > > On Wed, Apr 27, 2016 at 09:34:16PM -0400, Yuxin Ren wrote: > >> Hi, > >> > >> I am learning the URCU code. > >> > >> Why do we need rcu_gp_lock in synchronize_rcu? > >> https://github.com/urcu/userspace-rcu/blob/master/urcu.c#L401 > >> > >> In the comment, it says this lock ensures mutual exclusion between > >> threads calling synchronize_rcu(). > >> But only the first thread added to waiter queue can proceed to detect > >> grace period. > >> How can multiple threads currently perform the grace thread? > > > > They don't concurrently perform grace periods, and it would be wasteful > > for them to do so. Instead, the first one performs the grace period, > > and all that were waiting at the time it started get the benefit of that > > same grace period. > > > > Any that arrived after the first grace period performs the first > > grace period are served by whichever of them performs the second > > grace period. > > > > Thanx, Paul > > > _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev