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use new tracepoint support (iovisor#608)
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#!/usr/bin/python | ||
# | ||
# urandomread-explicit Example of instrumenting a kernel tracepoint. | ||
# For Linux, uses BCC, BPF. Embedded C. | ||
# | ||
# This is an older example of instrumenting a tracepoint, which defines | ||
# the argument struct and makes an explicit call to attach_tracepoint(). | ||
# See urandomread for a newer version that uses TRACEPOINT_PROBE(). | ||
# | ||
# REQUIRES: Linux 4.7+ (BPF_PROG_TYPE_TRACEPOINT support). | ||
# | ||
# Test by running this, then in another shell, run: | ||
# dd if=/dev/urandom of=/dev/null bs=1k count=5 | ||
# | ||
# Copyright 2016 Netflix, Inc. | ||
# Licensed under the Apache License, Version 2.0 (the "License") | ||
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from __future__ import print_function | ||
from bcc import BPF | ||
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# define BPF program | ||
bpf_text = """ | ||
#include <uapi/linux/ptrace.h> | ||
struct urandom_read_args { | ||
// from /sys/kernel/debug/tracing/events/random/urandom_read/format | ||
u64 __unused__; | ||
u32 got_bits; | ||
u32 pool_left; | ||
u32 input_left; | ||
}; | ||
int printarg(struct urandom_read_args *args) { | ||
bpf_trace_printk("%d\\n", args->got_bits); | ||
return 0; | ||
}; | ||
""" | ||
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# load BPF program | ||
b = BPF(text=bpf_text) | ||
b.attach_tracepoint("random:urandom_read", "printarg") | ||
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# header | ||
print("%-18s %-16s %-6s %s" % ("TIME(s)", "COMM", "PID", "GOTBITS")) | ||
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# format output | ||
while 1: | ||
try: | ||
(task, pid, cpu, flags, ts, msg) = b.trace_fields() | ||
except ValueError: | ||
continue | ||
print("%-18.9f %-16s %-6d %s" % (ts, task, pid, msg)) |
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