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samples/bpf: tracepoint example

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modify offwaketime to work with sched/sched_switch tracepoint
instead of kprobe into finish_task_switch

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2016-04-06 18:43:30 -07:00 committed by David S. Miller
parent c07660409e
commit 3c9b16448c
1 changed files with 23 additions and 5 deletions
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28
samples/bpf/offwaketime_kern.c
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@ -73,7 +73,7 @@ int waker(struct pt_regs *ctx)
return 0;
}
static inline int update_counts(struct pt_regs *ctx, u32 pid, u64 delta)
static inline int update_counts(void *ctx, u32 pid, u64 delta)
{
struct key_t key = {};
struct wokeby_t *woke;
@ -100,15 +100,33 @@ static inline int update_counts(struct pt_regs *ctx, u32 pid, u64 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[16];
int prev_pid;
int prev_prio;
long long prev_state;
char next_comm[16];
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);
u64 delta, ts, *tsp;
u32 pid;
/* record previous thread sleep time */
pid = _(p->pid);
u32 pid = _(p->pid);
#endif
u64 delta, ts, *tsp;
ts = bpf_ktime_get_ns();
bpf_map_update_elem(&start, &pid, &ts, BPF_ANY);