BatchPerCPU: add an example

Signed-off-by: Alun Evans <[email protected]>

examples/kprobe_percpu/main.go

@@ -8,6 +8,7 @@ import (
 	"log"
 	"time"
 
+	"github.com/cilium/ebpf"
 	"github.com/cilium/ebpf/link"
 	"github.com/cilium/ebpf/rlimit"
 )
@@ -50,14 +51,27 @@ func main() {
 
 	log.Println("Waiting for events..")
 
+	batch := true
 	for range ticker.C {
 		var all_cpu_value []uint64
-		if err := objs.KprobeMap.Lookup(mapKey, &all_cpu_value); err != nil {
-			log.Fatalf("reading map: %v", err)
+		if batch {
+			var nextKeyOut uint32
+			lookupKeys := make([]uint32, 2)
+			lookupValues := make([][]uint64, 2)
+			count, err := objs.KprobeMap.BatchLookup(nil, &nextKeyOut, lookupKeys, lookupValues, &ebpf.BatchOptions{})
+			if count != 1 {
+				log.Fatalf("batch reading map: %v", err)
+			}
+			all_cpu_value = lookupValues[0]
+		} else {
+			if err := objs.KprobeMap.Lookup(mapKey, &all_cpu_value); err != nil {
+				log.Fatalf("reading map: %v", err)
+			}
 		}
 		for cpuid, cpuvalue := range all_cpu_value {
 			log.Printf("%s called %d times on CPU%v\n", fn, cpuvalue, cpuid)
 		}
+		batch = !batch
 		log.Printf("\n")
 	}
 }