summaryrefslogtreecommitdiffstats
path: root/samples/bpf/offwaketime_kern.c
diff options
context:
space:
mode:
Diffstat (limited to 'samples/bpf/offwaketime_kern.c')
-rw-r--r--samples/bpf/offwaketime_kern.c158
1 files changed, 158 insertions, 0 deletions
diff --git a/samples/bpf/offwaketime_kern.c b/samples/bpf/offwaketime_kern.c
new file mode 100644
index 000000000..eb4d94742
--- /dev/null
+++ b/samples/bpf/offwaketime_kern.c
@@ -0,0 +1,158 @@
+/* Copyright (c) 2016 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/ptrace.h>
+#include <uapi/linux/perf_event.h>
+#include <linux/version.h>
+#include <linux/sched.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#define _(P) \
+ ({ \
+ typeof(P) val; \
+ bpf_probe_read_kernel(&val, sizeof(val), &(P)); \
+ val; \
+ })
+
+#define MINBLOCK_US 1
+#define MAX_ENTRIES 10000
+
+struct key_t {
+ char waker[TASK_COMM_LEN];
+ char target[TASK_COMM_LEN];
+ u32 wret;
+ u32 tret;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __type(key, struct key_t);
+ __type(value, u64);
+ __uint(max_entries, MAX_ENTRIES);
+} counts SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __type(key, u32);
+ __type(value, u64);
+ __uint(max_entries, MAX_ENTRIES);
+} start SEC(".maps");
+
+struct wokeby_t {
+ char name[TASK_COMM_LEN];
+ u32 ret;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __type(key, u32);
+ __type(value, struct wokeby_t);
+ __uint(max_entries, MAX_ENTRIES);
+} wokeby SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_STACK_TRACE);
+ __uint(key_size, sizeof(u32));
+ __uint(value_size, PERF_MAX_STACK_DEPTH * sizeof(u64));
+ __uint(max_entries, MAX_ENTRIES);
+} stackmap SEC(".maps");
+
+#define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
+
+SEC("kprobe/try_to_wake_up")
+int waker(struct pt_regs *ctx)
+{
+ struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
+ struct wokeby_t woke;
+ u32 pid;
+
+ pid = _(p->pid);
+
+ bpf_get_current_comm(&woke.name, sizeof(woke.name));
+ woke.ret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
+
+ bpf_map_update_elem(&wokeby, &pid, &woke, BPF_ANY);
+ return 0;
+}
+
+static inline int update_counts(void *ctx, u32 pid, u64 delta)
+{
+ struct wokeby_t *woke;
+ u64 zero = 0, *val;
+ struct key_t key;
+
+ __builtin_memset(&key.waker, 0, sizeof(key.waker));
+ bpf_get_current_comm(&key.target, sizeof(key.target));
+ key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
+ key.wret = 0;
+
+ woke = bpf_map_lookup_elem(&wokeby, &pid);
+ if (woke) {
+ key.wret = woke->ret;
+ __builtin_memcpy(&key.waker, woke->name, sizeof(key.waker));
+ bpf_map_delete_elem(&wokeby, &pid);
+ }
+
+ val = bpf_map_lookup_elem(&counts, &key);
+ if (!val) {
+ bpf_map_update_elem(&counts, &key, &zero, BPF_NOEXIST);
+ val = bpf_map_lookup_elem(&counts, &key);
+ if (!val)
+ return 0;
+ }
+ (*val) += delta;
+ return 0;
+}
+
+#if 1
+/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+struct sched_switch_args {
+ unsigned long long pad;
+ char prev_comm[TASK_COMM_LEN];
+ int prev_pid;
+ int prev_prio;
+ long long prev_state;
+ char next_comm[TASK_COMM_LEN];
+ int next_pid;
+ int next_prio;
+};
+SEC("tracepoint/sched/sched_switch")
+int oncpu(struct sched_switch_args *ctx)
+{
+ /* record previous thread sleep time */
+ u32 pid = ctx->prev_pid;
+#else
+SEC("kprobe/finish_task_switch")
+int oncpu(struct pt_regs *ctx)
+{
+ struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
+ /* record previous thread sleep time */
+ u32 pid = _(p->pid);
+#endif
+ u64 delta, ts, *tsp;
+
+ ts = bpf_ktime_get_ns();
+ bpf_map_update_elem(&start, &pid, &ts, BPF_ANY);
+
+ /* calculate current thread's delta time */
+ pid = bpf_get_current_pid_tgid();
+ tsp = bpf_map_lookup_elem(&start, &pid);
+ if (!tsp)
+ /* missed start or filtered */
+ return 0;
+
+ delta = bpf_ktime_get_ns() - *tsp;
+ bpf_map_delete_elem(&start, &pid);
+ delta = delta / 1000;
+ if (delta < MINBLOCK_US)
+ return 0;
+
+ return update_counts(ctx, pid, delta);
+}
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;