> -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Rahul Lakkireddy > Sent: Monday, October 05, 2015 11:06 AM > To: Aaron Conole > Cc: dev at dpdk.org; Felix Marti; Kumar A S; Nirranjan Kirubaharan > Subject: Re: [dpdk-dev] [PATCH 1/6] cxgbe: Optimize forwarding performance > for 40G > > Hi Aaron, > > On Friday, October 10/02/15, 2015 at 14:48:28 -0700, Aaron Conole wrote: > > Hi Rahul, > > > > Rahul Lakkireddy <rahul.lakkireddy at chelsio.com> writes: > > > > > Update sge initialization with respect to free-list manager configuration > > > and ingress arbiter. Also update refill logic to refill mbufs only after > > > a certain threshold for rx. Optimize tx packet prefetch and free. > > <<snip>> > > > for (i = 0; i < sd->coalesce.idx; i++) { > > > - rte_pktmbuf_free(sd->coalesce.mbuf[i]); > > > + struct rte_mbuf *tmp = sd->coalesce.mbuf[i]; > > > + > > > + do { > > > + struct rte_mbuf *next = tmp->next; > > > + > > > + rte_pktmbuf_free_seg(tmp); > > > + tmp = next; > > > + } while (tmp); > > > sd->coalesce.mbuf[i] = NULL; > > Pardon my ignorance here, but rte_pktmbuf_free does this work. I can't > > actually see much difference between your rewrite of this block, and > > the implementation of rte_pktmbuf_free() (apart from moving your branch > > to the end of the function). Did your microbenchmarking really show this > > as an improvement? > > > > Thanks for your time, > > Aaron > > rte_pktmbuf_free calls rte_mbuf_sanity_check which does a lot of > checks.
Only when RTE_LIBRTE_MBUF_DEBUG is enabled in your config. By default it is switched off. > This additional check seems redundant for single segment > packets since rte_pktmbuf_free_seg also performs rte_mbuf_sanity_check. > > Several PMDs already prefer to use rte_pktmbuf_free_seg directly over > rte_pktmbuf_free as it is faster. Other PMDs use rte_pktmbuf_free_seg() as each TD has an associated with it segment. So as HW is done with the TD, SW frees associated segment. In your case I don't see any point in re-implementing rte_pktmbuf_free() manually, and I don't think it would be any faster. Konstantin > > The forwarding perf. improvement with only this particular block is > around 1 Mpps for 64B packets when using l3fwd with 8 queues. > > Thanks, > Rahul
