FM / tracing

/usr/share/doc/bpfcc-tools/examples/tracing/

/usr/share/doc/bpfcc-tools/examples/tracing

Name	Size	Mode	Actions
biolatpcts.py	3312	0755	edit dl rm
biolatpcts_example.txt	650	0644	edit dl rm
bitehist.py	1397	0755	edit dl rm
bitehist_example.txt	1208	0644	edit dl rm
CMakeLists.txt	276	0644	edit dl rm
dddos.py	3818	0755	edit dl rm
dddos_example.txt	2112	0644	edit dl rm
disksnoop.py	1947	0755	edit dl rm
disksnoop_example.txt	1587	0644	edit dl rm
hello_fields.py	679	0755	edit dl rm
hello_perf_output.py	1270	0755	edit dl rm
hello_perf_output_using_ns.py	1843	0755	edit dl rm
kvm_hypercall.py	1520	0755	edit dl rm
kvm_hypercall.txt	1782	0644	edit dl rm
mallocstacks.py	1942	0755	edit dl rm
mysqld_query.py	1701	0755	edit dl rm
mysqld_query_example.txt	499	0644	edit dl rm
nflatency.py	6214	0755	edit dl rm
nodejs_http_server.py	1376	0755	edit dl rm
nodejs_http_server_example.txt	276	0644	edit dl rm
stacksnoop.py	3252	0755	edit dl rm
stacksnoop_example.txt	2871	0644	edit dl rm
stack_buildid_example.py	3106	0755	edit dl rm
strlen_count.py	1331	0755	edit dl rm
strlen_hist.py	1856	0755	edit dl rm
strlen_hist_ifunc.py	3800	0755	edit dl rm
strlen_snoop.py	1384	0755	edit dl rm
sync_timing.py	1390	0755	edit dl rm
task_switch.c	499	0644	edit dl rm
task_switch.py	486	0755	edit dl rm
tcpv4connect.py	2413	0755	edit dl rm
tcpv4connect_example.txt	1063	0644	edit dl rm
trace_fields.py	589	0755	edit dl rm
trace_perf_output.py	1600	0755	edit dl rm
undump.py	3602	0755	edit dl rm
undump_example.txt	886	0644	edit dl rm
urandomread-explicit.py	1511	0755	edit dl rm
urandomread.py	1032	0755	edit dl rm
urandomread_example.txt	675	0644	edit dl rm
vfsreadlat.c	896	0644	edit dl rm
vfsreadlat.py	1336	0755	edit dl rm
vfsreadlat_example.txt	3619	0644	edit dl rm

Edit: /usr/share/doc/bpfcc-tools/examples/tracing/strlen_hist.py (1856B)

#!/usr/bin/python

#
# strlen_hist.py   Histogram of system-wide strlen return values
#
# A basic example of using uprobes along with a histogram to show
# distributions.
#
# Runs until ctrl-c is pressed.
#
# Copyright (c) PLUMgrid, Inc.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# Example output:
# $ sudo ./strlen_hist.py
# 22:12:52
#      strlen return:      : count     distribution
#          0 -> 1          : 2106     |****************                        |
#          2 -> 3          : 1172     |*********                               |
#          4 -> 7          : 3892     |******************************          |
#          8 -> 15         : 5096     |****************************************|
#         16 -> 31         : 2201     |*****************                       |
#         32 -> 63         : 547      |****                                    |
#         64 -> 127        : 106      |                                        |
#        128 -> 255        : 13       |                                        |
#        256 -> 511        : 27       |                                        |
#        512 -> 1023       : 6        |                                        |
#       1024 -> 2047       : 10       |                                        |
# ^C$
#

from __future__ import print_function
import bcc
import time

text = """
#include <uapi/linux/ptrace.h>
BPF_HISTOGRAM(dist);
int count(struct pt_regs *ctx) {
    dist.increment(bpf_log2l(PT_REGS_RC(ctx)));
    return 0;
}
"""

b = bcc.BPF(text=text)
sym="strlen"
b.attach_uretprobe(name="c", sym=sym, fn_name="count")

dist = b["dist"]

try:
    while True:
        time.sleep(1)
        print("%-8s\n" % time.strftime("%H:%M:%S"), end="")
        dist.print_log2_hist(sym + " return:")
        dist.clear()

except KeyboardInterrupt:
    pass

cmd: