| #!/usr/bin/python |
| # |
| # disksnoop.py Trace block device I/O: basic version of iosnoop. |
| # For Linux, uses BCC, eBPF. See .c file. |
| # |
| # Written as a basic example of tracing latency. |
| # |
| # Copyright (c) 2015 Brendan Gregg. |
| # Licensed under the Apache License, Version 2.0 (the "License") |
| # |
| # 11-Aug-2015 Brendan Gregg Created this. |
| |
| from __future__ import print_function |
| from bpf import BPF |
| import sys |
| |
| REQ_WRITE = 1 # from include/linux/blk_types.h |
| |
| # load BPF program |
| b = BPF(src_file="disksnoop.c") |
| b.attach_kprobe(event="blk_start_request", fn_name="do_request") |
| b.attach_kprobe(event="blk_update_request", fn_name="do_completion") |
| |
| # header |
| print("%-18s %-2s %-7s %8s" % ("TIME(s)", "T", "BYTES", "LAT(ms)")) |
| |
| # open trace pipe |
| try: |
| trace = open("/sys/kernel/debug/tracing/trace_pipe", "r") |
| except: |
| print("ERROR: opening trace_pipe", file=sys.stderr) |
| exit(1) |
| |
| # format output |
| while 1: |
| (task, pid, cpu, flags, ts, msg) = b.trace_readline_fields() |
| (bytes_s, bflags_s, us_s) = msg.split() |
| |
| if int(bflags_s, 16) & REQ_WRITE: |
| type_s = "W" |
| elif bytes_s == "0": # see blk_fill_rwbs() for logic |
| type_s = "M" |
| else: |
| type_s = "R" |
| ms = float(int(us_s, 10)) / 1000 |
| |
| print("%-18.9f %-2s %-7s %8.2f" % (ts, type_s, bytes_s, ms)) |