| Message ID | 371de981d1aeabb8746e2732bb38e02aac6d75e2.1524137013.git.echaudro@redhat.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [ovs-dev] ofproto-dpif-upcall: Only call ovsrcu_postpone() on active actions | expand |
On Thu, Apr 19, 2018 at 01:24:06PM +0200, Eelco Chaudron wrote: > Currently, ovsrcu_postpone() is called even with a NULL argument, > i.e. when there is no data to be freed. This is causing additional > overhead because work is scheduled for the urcu thread. This change > avoids adding the postpone callback if no work needs to be done. > > This especially helps for the OVS-DPDK case where the PMD threads > might no longer have to do a write() due to the latch_set(), and thus > saving a syscall. > > Signed-off-by: Eelco Chaudron <echaudro@redhat.com> Wow, good catch! Thanks, I applied this to master.
diff --git a/ofproto/ofproto-dpif-upcall.c b/ofproto/ofproto-dpif-upcall.c index 00160e1ee..d26f201f4 100644 --- a/ofproto/ofproto-dpif-upcall.c +++ b/ofproto/ofproto-dpif-upcall.c @@ -1621,8 +1621,13 @@ ukey_get_actions(struct udpif_key *ukey, const struct nlattr **actions, size_t * static void ukey_set_actions(struct udpif_key *ukey, const struct ofpbuf *actions) { - ovsrcu_postpone(ofpbuf_delete, - ovsrcu_get_protected(struct ofpbuf *, &ukey->actions)); + struct ofpbuf *old_actions = ovsrcu_get_protected(struct ofpbuf *, + &ukey->actions); + + if (old_actions) { + ovsrcu_postpone(ofpbuf_delete, old_actions); + } + ovsrcu_set(&ukey->actions, ofpbuf_clone(actions)); }
Currently, ovsrcu_postpone() is called even with a NULL argument, i.e. when there is no data to be freed. This is causing additional overhead because work is scheduled for the urcu thread. This change avoids adding the postpone callback if no work needs to be done. This especially helps for the OVS-DPDK case where the PMD threads might no longer have to do a write() due to the latch_set(), and thus saving a syscall. Signed-off-by: Eelco Chaudron <echaudro@redhat.com> --- ofproto/ofproto-dpif-upcall.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)