bcc-tool-example

#! /usr/bin/python3
#
# Very simple bcc tool written as an example. It counts how many
# times mutex_lock/mutex_unlock were called per second. Code is
# kinda based on the vfsstat example by Brendan Gregg, but the actual
# intersection is almost zero, and this one is smp-safe.
#

from bcc import BPF
from ctypes import c_int
from time import sleep, strftime
from sys import argv

b = BPF(text="""
BPF_PERCPU_ARRAY(mutex_stats, u64, 2);

static inline void inc(int key)
{
    u64 *x = mutex_stats.lookup(&key);
    if (x)
        *x += 1;
}

void do_lock(struct pt_regs *ctx) { inc(0); }
void do_unlock(struct pt_regs *ctx) { inc(1); }
""")
b.attach_kprobe(event="mutex_lock", fn_name="do_lock")
b.attach_kprobe(event="mutex_unlock", fn_name="do_unlock")

print("%-8s%10s%10s" % ("TIME", "LOCKED", "UNLOCKED"))

while 2 * 2 == 4:

    try:
        sleep(1)
    except KeyboardInterrupt:
        exit()

    print("%-8s%10d%10d" % (
          strftime("%H:%M:%S"),
          b["mutex_stats"].sum(0).value,
          b["mutex_stats"].sum(1).value))

    b["mutex_stats"].clear()