On Aug 28, 2014, at 9:32 AM, Ben Pfaff <b...@nicira.com> wrote: > On Fri, Aug 22, 2014 at 01:58:17PM -0700, Jarno Rajahalme wrote: >> barrier->count is used as a simple counter and is not expected the >> synchronize the state of any other variable, so we can use atomic_count, >> which uses relaxed atomics. >> >> Ditto for the 'next_id' within ovsthread_wrapper(). >> >> Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com> > > I would have thought that ovs_barrier_block() would include a fairly > strong barrier--at least an acquire-release barrier?--but it doesn't > seem to necessarily include one at all now.
Yes, it would seem reasonable to expect that the effects of all participating threads would be visible on return from ovs_barrier_block(). Even after this change the seq_read() does that (due to ovs_mutex_lock() and ovs_mutex_unlock(), which have acquire and release semantics, respectively). However, seq_read() could be implemented without using a mutex, so it would be better to not rely on it. I’ll post a v2 on this to address this, thanks! Jarno _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
