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executable file
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#!/usr/bin/python
# @lint-avoid-python-3-compatibility-imports
#
# biotop block device (disk) I/O by process.
# For Linux, uses BCC, eBPF.
#
# USAGE: biotop.py [-h] [-C] [-r MAXROWS] [interval] [count]
#
# This uses in-kernel eBPF maps to cache process details (PID and comm) by I/O
# request, as well as a starting timestamp for calculating I/O latency.
#
# Copyright 2016 Netflix, Inc.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 06-Feb-2016 Brendan Gregg Created this.
from __future__ import print_function
from bcc import BPF
from time import sleep, strftime
import argparse
import signal
from subprocess import call
# arguments
examples = """examples:
./biotop # block device I/O top, 1 second refresh
./biotop -C # don't clear the screen
./biotop 5 # 5 second summaries
./biotop 5 10 # 5 second summaries, 10 times only
"""
parser = argparse.ArgumentParser(
description="Block device (disk) I/O by process",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
parser.add_argument("-C", "--noclear", action="store_true",
help="don't clear the screen")
parser.add_argument("-r", "--maxrows", default=20,
help="maximum rows to print, default 20")
parser.add_argument("interval", nargs="?", default=1,
help="output interval, in seconds")
parser.add_argument("count", nargs="?", default=99999999,
help="number of outputs")
args = parser.parse_args()
interval = int(args.interval)
countdown = int(args.count)
maxrows = int(args.maxrows)
clear = not int(args.noclear)
# linux stats
loadavg = "/proc/loadavg"
diskstats = "/proc/diskstats"
# signal handler
def signal_ignore(signal, frame):
print()
# load BPF program
b = BPF(text="""
#include <uapi/linux/ptrace.h>
#include <linux/blkdev.h>
// for saving process info by request
struct who_t {
u32 pid;
char name[TASK_COMM_LEN];
};
// the key for the output summary
struct info_t {
u32 pid;
int rwflag;
int major;
int minor;
char name[TASK_COMM_LEN];
};
// the value of the output summary
struct val_t {
u64 bytes;
u64 us;
u32 io;
};
BPF_HASH(start, struct request *);
BPF_HASH(whobyreq, struct request *, struct who_t);
BPF_HASH(counts, struct info_t, struct val_t);
// cache PID and comm by-req
int trace_pid_start(struct pt_regs *ctx, struct request *req)
{
struct who_t who = {};
if (bpf_get_current_comm(&who.name, sizeof(who.name)) == 0) {
who.pid = bpf_get_current_pid_tgid();
whobyreq.update(&req, &who);
}
return 0;
}
// time block I/O
int trace_req_start(struct pt_regs *ctx, struct request *req)
{
u64 ts;
ts = bpf_ktime_get_ns();
start.update(&req, &ts);
return 0;
}
// output
int trace_req_completion(struct pt_regs *ctx, struct request *req)
{
u64 *tsp;
// fetch timestamp and calculate delta
tsp = start.lookup(&req);
if (tsp == 0) {
return 0; // missed tracing issue
}
struct who_t *whop;
struct val_t *valp, zero = {};
u64 delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
// setup info_t key
struct info_t info = {};
info.major = req->rq_disk->major;
info.minor = req->rq_disk->first_minor;
/*
* The following deals with a kernel version change (in mainline 4.7, although
* it may be backported to earlier kernels) with how block request write flags
* are tested. We handle both pre- and post-change versions here. Please avoid
* kernel version tests like this as much as possible: they inflate the code,
* test, and maintenance burden.
*/
#ifdef REQ_WRITE
info.rwflag = !!(req->cmd_flags & REQ_WRITE);
#elif defined(REQ_OP_SHIFT)
info.rwflag = !!((req->cmd_flags >> REQ_OP_SHIFT) == REQ_OP_WRITE);
#else
info.rwflag = !!((req->cmd_flags & REQ_OP_MASK) == REQ_OP_WRITE);
#endif
whop = whobyreq.lookup(&req);
if (whop == 0) {
// missed pid who, save stats as pid 0
valp = counts.lookup_or_init(&info, &zero);
} else {
info.pid = whop->pid;
__builtin_memcpy(&info.name, whop->name, sizeof(info.name));
valp = counts.lookup_or_init(&info, &zero);
}
// save stats
valp->us += delta_us;
valp->bytes += req->__data_len;
valp->io++;
start.delete(&req);
whobyreq.delete(&req);
return 0;
}
""", debug=0)
b.attach_kprobe(event="blk_account_io_start", fn_name="trace_pid_start")
b.attach_kprobe(event="blk_start_request", fn_name="trace_req_start")
b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_req_start")
b.attach_kprobe(event="blk_account_io_completion",
fn_name="trace_req_completion")
print('Tracing... Output every %d secs. Hit Ctrl-C to end' % interval)
# cache disk major,minor -> diskname
disklookup = {}
with open(diskstats) as stats:
for line in stats:
a = line.split()
disklookup[a[0] + "," + a[1]] = a[2]
# output
exiting = 0
while 1:
try:
sleep(interval)
except KeyboardInterrupt:
exiting = 1
# header
if clear:
call("clear")
else:
print()
with open(loadavg) as stats:
print("%-8s loadavg: %s" % (strftime("%H:%M:%S"), stats.read()))
print("%-6s %-16s %1s %-3s %-3s %-8s %5s %7s %6s" % ("PID", "COMM",
"D", "MAJ", "MIN", "DISK", "I/O", "Kbytes", "AVGms"))
# by-PID output
counts = b.get_table("counts")
line = 0
for k, v in reversed(sorted(counts.items(),
key=lambda counts: counts[1].bytes)):
# lookup disk
disk = str(k.major) + "," + str(k.minor)
if disk in disklookup:
diskname = disklookup[disk]
else:
diskname = "?"
# print line
avg_ms = (float(v.us) / 1000) / v.io
print("%-6d %-16s %1s %-3d %-3d %-8s %5s %7s %6.2f" % (k.pid,
k.name.decode(), "W" if k.rwflag else "R", k.major, k.minor,
diskname, v.io, v.bytes / 1024, avg_ms))
line += 1
if line >= maxrows:
break
counts.clear()
countdown -= 1
if exiting or countdown == 0:
print("Detaching...")
exit()