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Diffstat (limited to 'samples/bpf/offwaketime_kern.c')
| -rw-r--r-- | samples/bpf/offwaketime_kern.c | 158 |
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; |