> -----Original Message----- > From: Jerin Jacob [mailto:jerin.jacob at caviumnetworks.com] > Sent: Sunday, July 24, 2016 6:08 PM > To: dev at dpdk.org > Cc: thomas.monjalon at 6wind.com; Ananyev, Konstantin <konstantin.ananyev at > intel.com>; Jerin Jacob > <jerin.jacob at caviumnetworks.com> > Subject: [dpdk-dev] [PATCH] ring: fix sc dequeue performance issue > > Use of rte_smb_wmb() instead of rte_smb_rmb() in sc dequeue function creates > the additional overhead of waiting for all the STOREs to be > completed to local buffer from ring buffer memory. The sc dequeue function > demands only LOAD-STORE barrier where LOADs from ring > buffer memory needs to be completed before tail pointer update. Changing to > rte_smb_rmb() to enable the required LOAD-STORE barrier. > > Fixes: ecc7d10e448e ("ring: guarantee dequeue ordering before tail update") > > Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com> > --- > lib/librte_ring/rte_ring.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h index > f928324..0e22e69 100644 > --- a/lib/librte_ring/rte_ring.h > +++ b/lib/librte_ring/rte_ring.h > @@ -756,7 +756,7 @@ __rte_ring_sc_do_dequeue(struct rte_ring *r, void > **obj_table, > > /* copy in table */ > DEQUEUE_PTRS(); > - rte_smp_wmb(); > + rte_smp_rmb(); > > __RING_STAT_ADD(r, deq_success, n); > r->cons.tail = cons_next; > --
Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com> > 2.5.5
