On Thu, 2018-08-23 at 20:14 +0200, Jakub Kicinski wrote: > I asked Louis to run some tests while I'm travelling, and he reports > that my worry about reporting the extra stats was unfounded. Update > function does not show up in traces at all. It seems under stress > (generated with stress-ng) the thread dumping the stats in userspace > (in OvS it would be the revalidator) actually consumes less CPU in > __gnet_stats_copy_basic (0.4% less for ~2.0% total). > > Would this match with your results? I'm not sure why dumping would be > faster with your change..
Wild guess on my side: the relevant patch changes a bit the binary layout of the 'tc_action' struct, possibly (I still need to check with pahole) moving the tcf_lock and the stats field on different cachelines, reducing false sharing that could affect badly such test. Cheers, Paolo
