> -----Original Message----- > From: Darrell Ball [mailto:db...@vmware.com] > Sent: Friday, August 25, 2017 6:19 PM > To: Fischetti, Antonio <antonio.fische...@intel.com>; d...@openvswitch.org > Subject: Re: [ovs-dev] [PATCH v4] dpif-netdev: Avoid reading RSS hash when EMC > is disabled > > Hi Antonio > > On 8/25/17, 6:56 AM, "ovs-dev-boun...@openvswitch.org on behalf of > antonio.fische...@intel.com" <ovs-dev-boun...@openvswitch.org on behalf of > antonio.fische...@intel.com> wrote: > > When EMC is disabled the reading of RSS hash is skipped. > Also, for packets that are not recirculated it retrieves > the hash value without considering the recirc id. > > Signed-off-by: Antonio Fischetti <antonio.fische...@intel.com> > --- > > V4 > - reworked to remove dependencies from other patches in > patchset "Skip EMC for recirc pkts and other optimizations." > https://urldefense.proofpoint.com/v2/url?u=https- > 3A__mail.openvswitch.org_pipermail_ovs-2Ddev_2017- > 2DAugust_337320.html&d=DwICAg&c=uilaK90D4TOVoH58JNXRgQ&r=BVhFA09CGX7JQ5Ih- > uZnsw&m=7UGZunJeutRugFmidRAykhZFRYscZ2rUUmhF7Ys9IM8&s=hzVGT1bI3zOj_x9J5cu18Q2D5 > WLHdEC1qhQ-Gu--TEE&e= > > - measurements were repeated with the latest head of master. > > Port-to-Port Test > ================= > Software built with "-O2 -march=native -g". > > I measured the Rx rate regardless of pkt loss by sending 1 UDP > flow, > 64B packets, at the line-rate. > > 2 PMDs with 3 Tx queues. > > Flows setup: > in_port=dpdk0 actions=output:dpdk1 > in_port=dpdk1 actions=output:dpdk0 > > Results > ------- > Values are for the Rx rate in Mpps, regardless of packet loss. > > RSS column: > Yes: RSS hash is provided by the NIC > No: RSS is disabled and the 5-tuple hash must be > computed in software. > > Note: to simulate RSS disabled I added the line > dp_packet_rss_valid(struct dp_packet *p) > { > +return false; > #ifdef DPDK_NETDEV > > EMC column: > Yes: default probability insertion, > No: EMC disabled. > > Orig means Commit ID: > 75f9e007e7f7eb91461e238f882d1c539c56bb8d > > [Darrell] > It looks like the main benefit (+6% throughput) occurs > when RSS is not calculated by the NIC and emc is disabled. What are the common > cases when RSS is not generated by the NIC ?
[Antonio] A common case could be when packets are coming in from a VM. Also when the NIC does not provide a hash value, but this shouldn't be considered a common case I guess. > > > > +--------------+----------------+ > +-----+-----+ Orig | Orig + this | > | RSS | EMC | | patch | > +-----+-----+--------------+----------------+ > | Yes | Yes | 12.02, 11.38 | 12.18, 11.32 | > | Yes | No | 8.35, 8.36 | 8.36, 8.38 | > +-----+-----+--------------+----------------+ > | No | Yes | 9.91, 11.15 | 9.84, 11.08 | > | No | No | 7.83, 7.87 | 8.33, 8.35 | > +-----+-----+--------------+----------------+ > > --- > lib/dpif-netdev.c | 32 ++++++++++++++++++++++++++++---- > 1 file changed, 28 insertions(+), 4 deletions(-) > > diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c > index e2cd931..1157998 100644 > --- a/lib/dpif-netdev.c > +++ b/lib/dpif-netdev.c > @@ -4567,6 +4567,22 @@ dp_netdev_upcall(struct dp_netdev_pmd_thread *pmd, > struct dp_packet *packet_, > } > > static inline uint32_t > +dpif_netdev_packet_get_rss_hash_orig_pkt(struct dp_packet *packet, > + const struct miniflow *mf) > +{ > + uint32_t hash; > + > + if (OVS_LIKELY(dp_packet_rss_valid(packet))) { > + hash = dp_packet_get_rss_hash(packet); > + } else { > + hash = miniflow_hash_5tuple(mf, 0); > + dp_packet_set_rss_hash(packet, hash); > + } > + > + return hash; > +} > + > +static inline uint32_t > dpif_netdev_packet_get_rss_hash(struct dp_packet *packet, > const struct miniflow *mf) > { > @@ -4701,10 +4717,18 @@ emc_processing(struct dp_netdev_pmd_thread *pmd, > } > miniflow_extract(packet, &key->mf); > key->len = 0; /* Not computed yet. */ > - key->hash = dpif_netdev_packet_get_rss_hash(packet, &key->mf); > - > - /* If EMC is disabled skip emc_lookup */ > - flow = (cur_min == 0) ? NULL: emc_lookup(flow_cache, key); > + /* If EMC is disabled skip hash computation and emc_lookup */ > + if (OVS_LIKELY(cur_min)) { > + if (!md_is_valid) { > + key->hash = > dpif_netdev_packet_get_rss_hash_orig_pkt(packet, > + &key->mf); > + } else { > + key->hash = dpif_netdev_packet_get_rss_hash(packet, &key- > >mf); > + } > + flow = emc_lookup(flow_cache, key); > + } else { > + flow = NULL; > + } > if (OVS_LIKELY(flow)) { > dp_netdev_queue_batches(packet, flow, &key->mf, batches, > n_batches); > -- > 2.4.11 > > _______________________________________________ > dev mailing list > d...@openvswitch.org > https://urldefense.proofpoint.com/v2/url?u=https- > 3A__mail.openvswitch.org_mailman_listinfo_ovs- > 2Ddev&d=DwICAg&c=uilaK90D4TOVoH58JNXRgQ&r=BVhFA09CGX7JQ5Ih- > uZnsw&m=7UGZunJeutRugFmidRAykhZFRYscZ2rUUmhF7Ys9IM8&s=azu46pbDSUX7cT7WFQXNZKhOT > fE96wI4CF4xgXGi7Go&e= > _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev