netstacklat: disable user_config.groupby_ifindex

Because production have too little traffic on the internal
interface that latency stats becomes unusable.

Via CONFIG_GROUPBY_IFINDEX also remove this from the
hist_key and note that YAML file also needs adjustments.

Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org>

Author: netoptimizer

examples/netstacklat.bpf.c

@@ -34,7 +34,7 @@ const struct netstacklat_bpf_config user_config = {
 	.filter_ifindex = true,
 	.filter_cgroup = true,
 	.filter_nonempty_sockqueue = false,
-	.groupby_ifindex = true,
+	.groupby_ifindex = false, /* If true also define CONFIG_GROUPBY_IFINDEX */
 	.groupby_cgroup = true,
 };
 
@@ -74,8 +74,13 @@ struct sk_buff___old {
  *  and "enabled" hooks.
  */
 #define N_CGROUPS	2 /* depend on cgroup_id_map matches in YAML config*/
+#ifdef CONFIG_GROUPBY_IFINDEX
 #define N_IFACES	6 /* On prod only interested in ext0 and vlan100@ext0 */
+#else
+#define N_IFACES	1 /* With groupby_ifindex==false */
+#endif
 #define N_HOOKS	1
+
 #if (CONFIG_HOOKS_EARLY_RCV || CONFIG_HOOKS_ENQUEUE || CONFIG_ENABLE_UDP_HOOKS)
 #err "Please update N_HOOKS"
 #endif
@@ -344,8 +349,10 @@ static void record_skb_latency(struct sk_buff *skb, struct sock *sk, enum netsta
 	if (!filter_nth_packet(hook))
 		return;
 
+#ifdef CONFIG_GROUPBY_IFINDEX
 	if (user_config.groupby_ifindex)
 		key.ifindex = ifindex;
+#endif
 
 	_record_latency_since(skb->tstamp, key);
 }
@@ -519,8 +526,10 @@ static void record_socket_latency(struct sock *sk, struct sk_buff *skb,
 	if (!filter_network_ns(skb, sk))
 		return;
 
+#ifdef CONFIG_GROUPBY_IFINDEX
 	if (user_config.groupby_ifindex)
 		key.ifindex = ifindex;
+#endif
 	if (user_config.groupby_cgroup)
 		key.cgroup = cgroup_id;
 

examples/netstacklat.h

@@ -59,17 +59,24 @@ enum netstacklat_hook {
 	NETSTACKLAT_N_HOOKS,
 };
 
+/* Disabling user_config.groupby_ifindex requires modifying hist_key and YAML
+ */
+//#define CONFIG_GROUPBY_IFINDEX 1
+#undef CONFIG_GROUPBY_IFINDEX
+
 /*
  * Key used for the histogram map
  * To be compatible with ebpf-exporter, all histograms need a key struct whose final
  * member is named "bucket" and is the histogram bucket index.
  */
 struct hist_key {
 	__u64 cgroup;
+#ifdef CONFIG_GROUPBY_IFINDEX
 	__u32 ifindex;
+#endif
 	__u16 hook; // need well defined size for ebpf-exporter to decode
 	__u16 bucket; // needs to be last to be compatible with ebpf-exporter
-};
+} __attribute__((packed));
 
 struct netstacklat_bpf_config {
 	__u32 network_ns;

examples/netstacklat.yaml

@@ -12,13 +12,14 @@ metrics:
           decoders:
             - name: uint
             - name: cgroup
-        - name: iface
-          size: 4
-          decoders:
-            # If including output from a different network namespace than ebpf-exporter
-            # you probably just want to decode as a uint (ifindex) instead
-            # - name: uint # For the ifname decoder you apparently don't first need a uint decoder like the others
-            - name: ifname
+# See: CONFIG_GROUPBY_IFINDEX
+#        - name: iface
+#          size: 4
+#          decoders:
+#            # If including output from a different network namespace than ebpf-exporter
+#            # you probably just want to decode as a uint (ifindex) instead
+#            # - name: uint # For the ifname decoder you apparently don't first need a uint decoder like the others
+#            - name: ifname
         - name: hook
           size: 2
           decoders: