Commit 439e53ca authored by Brenden Blanco's avatar Brenden Blanco

Merge pull request #70 from iovisor/ast_dev

example that shows usages of maps, probe_read, get_current_pid helpers
parents 14aa9da1 b6e43a26
#include <uapi/linux/ptrace.h>
#include <linux/sched.h>
struct key_t {
u32 prev_pid;
u32 curr_pid;
};
// map_type, key_type, leaf_type, table_name, num_entry
BPF_TABLE("hash", struct key_t, u64, stats, 1024);
int count_sched(struct pt_regs *ctx) {
struct key_t key = {};
u64 zero = 0, *val;
key.curr_pid = bpf_get_current_pid_tgid();
bpf_probe_read(&key.prev_pid, 4,
(void *)ctx->di + offsetof(struct task_struct, pid));
val = stats.lookup_or_init(&key, &zero);
(*val)++;
return 0;
}
#!/usr/bin/python
# Copyright (c) PLUMgrid, Inc.
# Licensed under the Apache License, Version 2.0 (the "License")
from bpf import BPF
from time import sleep
b = BPF(src_file="task_switch.c")
fn = b.load_func("count_sched", BPF.KPROBE)
stats = b.get_table("stats")
BPF.attach_kprobe(fn, "finish_task_switch")
# generate many schedule events
for i in range(0, 100): sleep(0.01)
for k, v in stats.items():
print("task_switch[%5d->%5d]=%u" % (k.prev_pid, k.curr_pid, v.value))
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