[ovs-dev] [PATCH v5] dpif-netdev: Avoid reading RSS hash when EMC is disabled
Darrell Ball
dball at vmware.com
Fri Sep 22 09:44:06 UTC 2017
I applied the patch to dpdk_merge here
https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_darball_ovs_commits_dpdk-5Fmerge&d=DwIGaQ&c=uilaK90D4TOVoH58JNXRgQ&r=BVhFA09CGX7JQ5Ih-uZnsw&m=A2_FCacqbp2moAo3HGFlTuxsjONUGhlN42OBcAuQQ6w&s=b6btPKhgvOFr2GOUYvktND6kaC6jc3fXI-mXfvNgXOU&e=
On 9/19/17, 2:46 AM, "O Mahony, Billy" <billy.o.mahony at intel.com> wrote:
Acked-by: Billy O'Mahony <billy.o.mahony at intel.com>
> -----Original Message-----
> From: Fischetti, Antonio
> Sent: Tuesday, September 12, 2017 5:34 PM
> To: dev at openvswitch.org
> Cc: Darrell Ball <dball at vmware.com>; O Mahony, Billy
> <billy.o.mahony at intel.com>; Fischetti, Antonio
> <antonio.fischetti at intel.com>
> Subject: [PATCH v5] dpif-netdev: Avoid reading RSS hash when EMC is
> disabled
>
> 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.
>
> CC: Darrell Ball <dball at vmware.com>
> CC: Billy O Mahony <billy.o.mahony at intel.com>
> Signed-off-by: Antonio Fischetti <antonio.fischetti at intel.com>
> ---
> V5
> - Removed OVS_LIKELY when checking cur_min.
>
> - I see a performance improvement for P2P and PVP tescases
> when EMC is disabled, measurements are below.
>
> - I also tried different solutions, eg passing md_is_valid
> to dpif_netdev_packet_get_rss_hash - or even the recirc_id
> computed inside dp_execute_cb - as suggested by Billy but
> I didn't see any performance benefit.
>
> - Rebased on Commit id
> b9fedfa61f000f49500973d2a51e99a80d9cf9b8
>
> - Each measurement was repeated 5 times and an average was
> computed.
>
>
> P2P testcase
> ------------
> Flow setup:
> table=0, in_port=dpdk0 actions=output:dpdk1 table=0, in_port=dpdk1
> actions=output:dpdk0
>
> Mono-directional, 64B UDP packets. Traffic sent at line-rate.
> PMD threads: 2
> Built with "-O2 -march=native -g"
>
> Measurements and average are in Mpps.
>
> Orig | 5 Measurments | Avg
> ---------+------------------------------------------+---------
> With EMC | 11.39 11.37 11.46 11.35 11.39 | 11.39
> no EMC | 8.23 8.22 8.26 8.20 8.22 | 8.23
>
> + patch | 5 Measurments | Avg
> ---------+------------------------------------------+---------
> With EMC | 11.46 11.39 11.40 11.45 11.38 | 11.42
> no EMC | 8.42 8.41 8.37 8.43 8.37 | 8.40
>
>
> PVP testcase
> ------------
> Flow setup:
> table=0, in_port=dpdk0 actions=output:dpdkvhostuser0 table=0,
> in_port=dpdkvhostuser0 actions=output:dpdk0 table=0,
> in_port=dpdkvhostuser1 actions=output:dpdk1 table=0, in_port=dpdk1
> actions=output:dpdkvhostuser1
>
> Bi-directional, 64B UDP packets. Traffic sent at line-rate.
> PMD threads: 2
> Built with "-O2 -march=native -g"
>
> Measurements and average are in Mpps.
>
> Orig | 5 Measurments | Avg
> ---------+------------------------------------------+---------
> With EMC | 4.59 4.60 4.46 4.59 4.59 | 4.57
> no EMC | 3.72 3.72 3.64 3.72 3.72 | 3.70
>
> + patch | 5 Measurments | Avg
> ---------+------------------------------------------+---------
> With EMC | 4.50 4.62 4.60 4.60 4.58 | 4.58
> no EMC | 3.78 3.86 3.84 3.84 3.83 | 3.83
>
>
> Recirculation testcase
> ----------------------
> In a test setup with a firewall I didn't see any performance difference
> between the original and the patch.
>
>
> 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_2017-2D&d=DwIFAg&c=uilaK90D4TOVoH58JNXRgQ&r=BVhFA09CGX7JQ5Ih-uZnsw&m=wEai262PgPsfbN-68LaqK00f7_-72ERM-R9kZ304XmQ&s=iuUIj3Y4ollBfrL0NZI8EXC_rbkCt_HY4-0na0AZNkg&e=
> August/337320.html
>
> - measurements were repeated with the latest head of master.
> ---
> 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 0ceef9d..baf65e8
> 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -4765,6 +4765,22 @@ 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) { @@ -4899,10 +4915,18 @@
> 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 (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
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