diff --git a/examples/tracing/urandomread-explicit.py b/examples/tracing/urandomread-explicit.py new file mode 100755 index 000000000000..e126192acf2d --- /dev/null +++ b/examples/tracing/urandomread-explicit.py @@ -0,0 +1,52 @@ +#!/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") + +from __future__ import print_function +from bcc import BPF + +# define BPF program +bpf_text = """ +#include + +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; +}; +""" + +# load BPF program +b = BPF(text=bpf_text) +b.attach_tracepoint("random:urandom_read", "printarg") + +# header +print("%-18s %-16s %-6s %s" % ("TIME(s)", "COMM", "PID", "GOTBITS")) + +# 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)) diff --git a/examples/tracing/urandomread.py b/examples/tracing/urandomread.py index b2a58bd52638..2f46bdaa9067 100755 --- a/examples/tracing/urandomread.py +++ b/examples/tracing/urandomread.py @@ -1,7 +1,7 @@ #!/usr/bin/python # -# tracepoint Example of instrumenting a kernel tracepoint. -# For Linux, uses BCC, BPF. Embedded C. +# urandomread Example of instrumenting a kernel tracepoint. +# For Linux, uses BCC, BPF. Embedded C. # # REQUIRES: Linux 4.7+ (BPF_PROG_TYPE_TRACEPOINT support). # @@ -14,28 +14,14 @@ from __future__ import print_function from bcc import BPF -# define BPF program -bpf_text = """ -#include - -struct urandom_read_args { - // from /sys/kernel/debug/tracing/events/random/urandom_read/format - // this may be automatically generated in a future bcc version - u64 __unused__; - u32 got_bits; - u32 pool_left; - u32 input_left; -}; - -int printarg(struct urandom_read_args *args) { +# load BPF program +b = BPF(text=""" +TRACEPOINT_PROBE(random, urandom_read) { + // args is from /sys/kernel/debug/tracing/events/random/urandom_read/format bpf_trace_printk("%d\\n", args->got_bits); return 0; }; -""" - -# load BPF program -b = BPF(text=bpf_text) -b.attach_tracepoint("random:urandom_read", "printarg") +""") # header print("%-18s %-16s %-6s %s" % ("TIME(s)", "COMM", "PID", "GOTBITS"))