attempt at fixing older kernels

Author: brycekahle

pkg/ebpf/c/lock_contention.c

@@ -476,7 +476,7 @@ SEC("tp_btf/contention_begin")
 int tracepoint__contention_begin(u64 *ctx)
 {
     struct tstamp_data *pelem;
-    struct lock_range range;
+    struct lock_range range = {};
 
     if (!can_record(ctx, &range))
     	return 0;

pkg/ebpf/lockcontention.go

@@ -40,7 +40,7 @@ const (
 	ioctlCollectLocksCmd = 0x70c13
 
 	// maximum lock ranges to track
-	maxTrackedRanges = 2048
+	maxTrackedRanges = 1024
 
 	// batch size when updating per cpu map storing lock ranges
 	// this value is the chunks in which we add the ranges to the per-cpu map