[ovs-dev] [PATCH v5 1/2] dpctl: dpif: add kernel datapath cache hit output

[Eelco Chaudron]

This patch adds cache usage statistics to the output:

$ ovs-dpctl show
system at ovs-system:
  lookups: hit:24 missed:71 lost:0
  flows: 0
  masks: hit:334 total:0 hit/pkt:3.52
  cache: hit:4 hit rate:4.21%
  port 0: ovs-system (internal)
  port 1: genev_sys_6081 (geneve: packet_type=ptap)
  port 2: br-int (internal)
  port 3: br-ex (internal)
  port 4: eth2
  port 5: sw1p1 (internal)
  port 6: sw0p4 (internal)

Signed-off-by: Eelco Chaudron <echaudro at redhat.com>

---
v2: - Changed cache naming to use a hyphen instead of spaces
    - Some error message grammar changes
    - Update dpctl man page
    - Add self tests to for the new set/get commands
v3: - Rebase on the latest master branch
v4: - Fixed commit message and tab/spaces in datapath include
v5: - Fixed tabs in openvswitch.h

 datapath/linux/compat/include/linux/openvswitch.h |    2 +-
 lib/dpctl.c                                       |    9 +++++++++
 lib/dpif-netdev.c                                 |    1 +
 lib/dpif-netlink.c                                |    9 +++++++++
 lib/dpif.h                                        |    2 ++
 5 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/datapath/linux/compat/include/linux/openvswitch.h b/datapath/linux/compat/include/linux/openvswitch.h
index 875de2025..9caef6fe7 100644
--- a/datapath/linux/compat/include/linux/openvswitch.h
+++ b/datapath/linux/compat/include/linux/openvswitch.h
@@ -122,8 +122,8 @@ struct ovs_dp_megaflow_stats {
 	__u64 n_mask_hit;	 /* Number of masks used for flow lookups. */
 	__u32 n_masks;		 /* Number of masks for the datapath. */
 	__u32 pad0;		 /* Pad for future expension. */
+	__u64 n_cache_hit;	 /* Number of cache matches for flow lookups. */
 	__u64 pad1;		 /* Pad for future expension. */
-	__u64 pad2;		 /* Pad for future expension. */
 };
 
 struct ovs_vport_stats {
diff --git a/lib/dpctl.c b/lib/dpctl.c
index ef8ae7402..acc677974 100644
--- a/lib/dpctl.c
+++ b/lib/dpctl.c
@@ -611,6 +611,15 @@ show_dpif(struct dpif *dpif, struct dpctl_params *dpctl_p)
             dpctl_print(dpctl_p, "  masks: hit:%"PRIu64" total:%"PRIu32
                                  " hit/pkt:%.2f\n",
                         stats.n_mask_hit, stats.n_masks, avg);
+
+            if (stats.n_cache_hit != UINT64_MAX) {
+                double avg_hits = n_pkts ?
+                    (double) stats.n_cache_hit / n_pkts * 100 : 0.0;
+
+                dpctl_print(dpctl_p,
+                            "  cache: hit:%"PRIu64" hit rate:%.2f%%\n",
+                            stats.n_cache_hit, avg_hits);
+            }
         }
     }
 
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 650e67ab3..8e7aa88cf 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -2026,6 +2026,7 @@ dpif_netdev_get_stats(const struct dpif *dpif, struct dpif_dp_stats *stats)
     }
     stats->n_masks = UINT32_MAX;
     stats->n_mask_hit = UINT64_MAX;
+    stats->n_cache_hit = UINT64_MAX;
 
     return 0;
 }
diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
index 73d5608a8..fd9b71d91 100644
--- a/lib/dpif-netlink.c
+++ b/lib/dpif-netlink.c
@@ -672,9 +672,18 @@ dpif_netlink_get_stats(const struct dpif *dpif_, struct dpif_dp_stats *stats)
             stats->n_masks = dp.megaflow_stats->n_masks;
             stats->n_mask_hit = get_32aligned_u64(
                 &dp.megaflow_stats->n_mask_hit);
+            stats->n_cache_hit = get_32aligned_u64(
+                &dp.megaflow_stats->n_cache_hit);
+
+            if (!stats->n_cache_hit) {
+                /* Old kernels don't use this field and always
+                 * report zero instead. Disable this stat. */
+                stats->n_cache_hit = UINT64_MAX;
+            }
         } else {
             stats->n_masks = UINT32_MAX;
             stats->n_mask_hit = UINT64_MAX;
+            stats->n_cache_hit = UINT64_MAX;
         }
         ofpbuf_delete(buf);
     }
diff --git a/lib/dpif.h b/lib/dpif.h
index f9728e673..0c6856f17 100644
--- a/lib/dpif.h
+++ b/lib/dpif.h
@@ -429,6 +429,8 @@ struct dpif_dp_stats {
     uint64_t n_missed;          /* Number of flow table misses. */
     uint64_t n_lost;            /* Number of misses not sent to userspace. */
     uint64_t n_flows;           /* Number of flows present. */
+    uint64_t n_cache_hit;       /* Number of mega flow mask cache hits for
+                                   flow table matches. */
     uint64_t n_mask_hit;        /* Number of mega flow masks visited for
                                    flow table matches. */
     uint32_t n_masks;           /* Number of mega flow masks. */