Merge pull request #305 from bobrik/ivan/increment-histogram

Convert existing examples to increment_exp2_histogram
cloudflare · Oct 18, 2023 · e750bac · e750bac
2 parents babfa4a + 0239007
commit e750bac
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Showing 4 changed files with 23 additions and 54 deletions.
diff --git a/examples/accept-latency.bpf.c b/examples/accept-latency.bpf.c
@@ -13,7 +13,7 @@
 
 struct socket_latency_key_t {
     u16 port;
-    u64 slot;
+    u64 bucket;
 };
 
 struct {
@@ -41,32 +41,21 @@ int BPF_KPROBE(kprobe__inet_csk_reqsk_queue_hash_add, struct sock *sk, struct re
 SEC("kprobe/inet_csk_accept")
 int BPF_KPROBE(kprobe__inet_csk_accept, struct sock *sk)
 {
-    u64 *tsp, delta_us, latency_slot;
+    u64 *tsp, delta_us, ts = bpf_ktime_get_ns();
     struct inet_connection_sock *icsk = (struct inet_connection_sock *) sk;
     struct request_sock *req = BPF_CORE_READ(icsk, icsk_accept_queue).rskq_accept_head;
-    struct socket_latency_key_t latency_key = {};
+    struct socket_latency_key_t key = {};
 
     tsp = bpf_map_lookup_elem(&start, &req);
     if (!tsp) {
         return 0;
     }
 
-    delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
+    delta_us = (ts - *tsp) / 1000;
 
-    // Latency histogram key
-    latency_slot = log2l(delta_us);
+    key.port = BPF_CORE_READ(sk, __sk_common).skc_num;
 
-    // Cap latency bucket at max value
-    if (latency_slot > MAX_LATENCY_SLOT) {
-        latency_slot = MAX_LATENCY_SLOT;
-    }
-
-    latency_key.port = BPF_CORE_READ(sk, __sk_common).skc_num;
-    latency_key.slot = latency_slot;
-    increment_map(&accept_latency_seconds, &latency_key, 1);
-
-    latency_key.slot = MAX_LATENCY_SLOT + 1;
-    increment_map(&accept_latency_seconds, &latency_key, delta_us);
+    increment_exp2_histogram(&accept_latency_seconds, key, delta_us, MAX_LATENCY_SLOT);
 
     bpf_map_delete_elem(&start, &req);
 

diff --git a/examples/biolatency.bpf.c b/examples/biolatency.bpf.c
@@ -18,7 +18,7 @@
 struct disk_latency_key_t {
     u32 dev;
     u8 op;
-    u64 slot;
+    u64 bucket;
 };
 
 extern int LINUX_KERNEL_VERSION __kconfig;
@@ -105,38 +105,25 @@ int block_rq_issue(struct bpf_raw_tracepoint_args *ctx)
 SEC("raw_tp/block_rq_complete")
 int block_rq_complete(struct bpf_raw_tracepoint_args *ctx)
 {
-    u64 *tsp, flags, delta_us, latency_slot;
+    u64 *tsp, flags, delta_us, ts = bpf_ktime_get_ns();
     struct gendisk *disk;
     struct request *rq = (struct request *) ctx->args[0];
-    struct disk_latency_key_t latency_key = {};
+    struct disk_latency_key_t key = {};
 
     tsp = bpf_map_lookup_elem(&start, &rq);
     if (!tsp) {
         return 0;
     }
 
-    // Delta in microseconds
-    delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
-
-    // Latency histogram key
-    latency_slot = log2l(delta_us);
-
-    // Cap latency bucket at max value
-    if (latency_slot > MAX_LATENCY_SLOT) {
-        latency_slot = MAX_LATENCY_SLOT;
-    }
+    delta_us = (ts - *tsp) / 1000;
 
     disk = get_disk(rq);
     flags = BPF_CORE_READ(rq, cmd_flags);
 
-    latency_key.slot = latency_slot;
-    latency_key.dev = disk ? MKDEV(BPF_CORE_READ(disk, major), BPF_CORE_READ(disk, first_minor)) : 0;
-    latency_key.op = flags & REQ_OP_MASK;
-
-    increment_map(&bio_latency_seconds, &latency_key, 1);
+    key.dev = disk ? MKDEV(BPF_CORE_READ(disk, major), BPF_CORE_READ(disk, first_minor)) : 0;
+    key.op = flags & REQ_OP_MASK;
 
-    latency_key.slot = MAX_LATENCY_SLOT + 1;
-    increment_map(&bio_latency_seconds, &latency_key, delta_us);
+    increment_exp2_histogram(&bio_latency_seconds, key, delta_us, MAX_LATENCY_SLOT);
 
     bpf_map_delete_elem(&start, &rq);
 

diff --git a/examples/shrinklat.bpf.c b/examples/shrinklat.bpf.c
@@ -6,6 +6,10 @@
 // 27 buckets for latency, max range is 33.6s .. 67.1s
 #define MAX_LATENCY_SLOT 26
 
+struct key_t {
+    u32 bucket;
+};
+
 struct {
     __uint(type, BPF_MAP_TYPE_HASH);
     __uint(max_entries, 10240);
@@ -16,7 +20,7 @@ struct {
 struct {
     __uint(type, BPF_MAP_TYPE_ARRAY);
     __uint(max_entries, MAX_LATENCY_SLOT + 1);
-    __type(key, u32);
+    __type(key, struct key_t);
     __type(value, u64);
 } shrink_node_latency_seconds SEC(".maps");
 
@@ -32,29 +36,18 @@ int shrink_node_enter(struct pt_regs *ctx)
 SEC("kretprobe/shrink_node")
 int shrink_node_exit(struct pt_regs *ctx)
 {
+    u64 *tsp, delta_us, ts = bpf_ktime_get_ns();
     u32 pid = bpf_get_current_pid_tgid();
-    u64 *tsp, latency_us, latency_slot;
+    struct key_t key = {};
 
     tsp = bpf_map_lookup_elem(&start, &pid);
     if (!tsp) {
         return 0;
     }
 
-    // Latency in microseconds
-    latency_us = (bpf_ktime_get_ns() - *tsp) / 1000;
-
-    // Latency histogram key
-    latency_slot = log2l(latency_us);
-
-    // Cap latency bucket at max value
-    if (latency_slot > MAX_LATENCY_SLOT) {
-        latency_slot = MAX_LATENCY_SLOT;
-    }
-
-    increment_map(&shrink_node_latency_seconds, &latency_slot, 1);
+    delta_us = (ts - *tsp) / 1000;
 
-    latency_slot = MAX_LATENCY_SLOT + 1;
-    increment_map(&shrink_node_latency_seconds, &latency_slot, latency_us);
+    increment_exp2_histogram(&shrink_node_latency_seconds, key, delta_us, MAX_LATENCY_SLOT);
 
     bpf_map_delete_elem(&start, &pid);
 

diff --git a/examples/shrinklat.yaml b/examples/shrinklat.yaml
@@ -8,6 +8,6 @@ metrics:
       bucket_multiplier: 0.000001 # microseconds to seconds
       labels:
         - name: bucket
-          size: 4
+          size: 8
           decoders:
             - name: uint