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Copy pathbiolatency
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executable file
·138 lines (122 loc) · 3.69 KB
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#!/usr/bin/python
#
# biolatency Summarize block device I/O latency as a histogram.
# For Linux, uses BCC, eBPF.
#
# USAGE: biolatency [-h] [-T] [-Q] [-m] [-D] [interval] [count]
#
# Copyright (c) 2015 Brendan Gregg.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 20-Sep-2015 Brendan Gregg Created this.
from __future__ import print_function
from bcc import BPF
from time import sleep, strftime
import argparse
# arguments
examples = """examples:
./biolatency # summarize block I/O latency as a histogram
./biolatency 1 10 # print 1 second summaries, 10 times
./biolatency -mT 1 # 1s summaries, milliseconds, and timestamps
./biolatency -Q # include OS queued time in I/O time
./biolatency -D # show each disk device separately
"""
parser = argparse.ArgumentParser(
description="Summarize block device I/O latency as a histogram",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
parser.add_argument("-T", "--timestamp", action="store_true",
help="include timestamp on output")
parser.add_argument("-Q", "--queued", action="store_true",
help="include OS queued time in I/O time")
parser.add_argument("-m", "--milliseconds", action="store_true",
help="millisecond histogram")
parser.add_argument("-D", "--disks", action="store_true",
help="print a histogram per disk device")
parser.add_argument("interval", nargs="?", default=99999999,
help="output interval, in seconds")
parser.add_argument("count", nargs="?", default=99999999,
help="number of outputs")
args = parser.parse_args()
countdown = int(args.count)
debug = 0
# define BPF program
bpf_text = """
#include <uapi/linux/ptrace.h>
#include <linux/blkdev.h>
typedef struct disk_key {
char disk[DISK_NAME_LEN];
u64 slot;
} disk_key_t;
BPF_HASH(start, struct request *);
STORAGE
// time block I/O
int trace_req_start(struct pt_regs *ctx, struct request *req)
{
u64 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, delta;
// fetch timestamp and calculate delta
tsp = start.lookup(&req);
if (tsp == 0) {
return 0; // missed issue
}
delta = bpf_ktime_get_ns() - *tsp;
FACTOR
// store as histogram
STORE
start.delete(&req);
return 0;
}
"""
# code substitutions
if args.milliseconds:
bpf_text = bpf_text.replace('FACTOR', 'delta /= 1000000;')
label = "msecs"
else:
bpf_text = bpf_text.replace('FACTOR', 'delta /= 1000;')
label = "usecs"
if args.disks:
bpf_text = bpf_text.replace('STORAGE',
'BPF_HISTOGRAM(dist, disk_key_t);')
bpf_text = bpf_text.replace('STORE',
'disk_key_t key = {.slot = bpf_log2l(delta)}; ' +
'bpf_probe_read(&key.disk, sizeof(key.disk), ' +
'req->rq_disk->disk_name); dist.increment(key);')
else:
bpf_text = bpf_text.replace('STORAGE', 'BPF_HISTOGRAM(dist);')
bpf_text = bpf_text.replace('STORE',
'dist.increment(bpf_log2l(delta));')
if debug:
print(bpf_text)
# load BPF program
b = BPF(text=bpf_text)
if args.queued:
b.attach_kprobe(event="blk_account_io_start", fn_name="trace_req_start")
else:
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 block device I/O... Hit Ctrl-C to end.")
# output
exiting = 0 if args.interval else 1
dist = b.get_table("dist")
while (1):
try:
sleep(int(args.interval))
except KeyboardInterrupt:
exiting=1
print()
if args.timestamp:
print("%-8s\n" % strftime("%H:%M:%S"), end="")
dist.print_log2_hist(label, "disk")
dist.clear()
countdown -= 1
if exiting or countdown == 0:
exit()