414 lines
11 KiB
Python
Executable File
414 lines
11 KiB
Python
Executable File
#! /usr/bin/python3
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# @lint-avoid-python-3-compatibility-imports
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#
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# biolatency Summarize block device I/O latency as a histogram.
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# For Linux, uses BCC, eBPF.
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#
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# USAGE: biolatency [-h] [-T] [-Q] [-m] [-D] [-F] [-e] [-j] [-d DISK] [interval] [count]
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#
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# Copyright (c) 2015 Brendan Gregg.
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# Licensed under the Apache License, Version 2.0 (the "License")
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#
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# 20-Sep-2015 Brendan Gregg Created this.
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# 31-Mar-2022 Rocky Xing Added disk filter support.
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# 01-Aug-2023 Jerome Marchand Added support for block tracepoints
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from __future__ import print_function
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from bcc import BPF
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from time import sleep, strftime
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import argparse
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import ctypes as ct
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import os
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# arguments
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examples = """examples:
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./biolatency # summarize block I/O latency as a histogram
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./biolatency 1 10 # print 1 second summaries, 10 times
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./biolatency -mT 1 # 1s summaries, milliseconds, and timestamps
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./biolatency -Q # include OS queued time in I/O time
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./biolatency -D # show each disk device separately
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./biolatency -F # show I/O flags separately
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./biolatency -j # print a dictionary
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./biolatency -e # show extension summary(total, average)
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./biolatency -d sdc # Trace sdc only
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"""
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parser = argparse.ArgumentParser(
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description="Summarize block device I/O latency as a histogram",
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formatter_class=argparse.RawDescriptionHelpFormatter,
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epilog=examples)
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parser.add_argument("-T", "--timestamp", action="store_true",
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help="include timestamp on output")
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parser.add_argument("-Q", "--queued", action="store_true",
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help="include OS queued time in I/O time")
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parser.add_argument("-m", "--milliseconds", action="store_true",
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help="millisecond histogram")
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parser.add_argument("-D", "--disks", action="store_true",
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help="print a histogram per disk device")
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parser.add_argument("-F", "--flags", action="store_true",
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help="print a histogram per set of I/O flags")
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parser.add_argument("-e", "--extension", action="store_true",
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help="summarize average/total value")
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parser.add_argument("interval", nargs="?", default=99999999,
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help="output interval, in seconds")
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parser.add_argument("count", nargs="?", default=99999999,
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help="number of outputs")
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parser.add_argument("--ebpf", action="store_true",
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help=argparse.SUPPRESS)
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parser.add_argument("-j", "--json", action="store_true",
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help="json output")
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parser.add_argument("-d", "--disk", type=str,
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help="Trace this disk only")
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args = parser.parse_args()
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countdown = int(args.count)
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debug = 0
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if args.flags and args.disks:
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print("ERROR: can only use -D or -F. Exiting.")
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exit()
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# define BPF program
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bpf_text = """
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#include <uapi/linux/ptrace.h>
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#include <linux/blk-mq.h>
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typedef struct disk_key {
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dev_t dev;
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u64 slot;
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} disk_key_t;
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typedef struct flag_key {
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u64 flags;
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u64 slot;
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} flag_key_t;
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typedef struct ext_val {
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u64 total;
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u64 count;
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} ext_val_t;
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struct tp_args {
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u64 __unused__;
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dev_t dev;
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sector_t sector;
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unsigned int nr_sector;
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unsigned int bytes;
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char rwbs[8];
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char comm[16];
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char cmd[];
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};
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struct start_key {
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dev_t dev;
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u32 _pad;
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sector_t sector;
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CMD_FLAGS
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};
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BPF_HASH(start, struct start_key);
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STORAGE
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static dev_t ddevt(struct gendisk *disk) {
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return (disk->major << 20) | disk->first_minor;
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}
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// time block I/O
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static int __trace_req_start(struct start_key key)
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{
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DISK_FILTER
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u64 ts = bpf_ktime_get_ns();
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start.update(&key, &ts);
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return 0;
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}
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int trace_req_start(struct pt_regs *ctx, struct request *req)
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{
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struct start_key key = {
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.dev = ddevt(req->__RQ_DISK__),
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.sector = req->__sector
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};
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SET_FLAGS
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return __trace_req_start(key);
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}
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int trace_req_start_tp(struct tp_args *args)
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{
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struct start_key key = {
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.dev = args->dev,
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.sector = args->sector
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};
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return __trace_req_start(key);
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}
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// output
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static int __trace_req_done(struct start_key key)
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{
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u64 *tsp, delta;
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// fetch timestamp and calculate delta
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tsp = start.lookup(&key);
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if (tsp == 0) {
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return 0; // missed issue
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}
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delta = bpf_ktime_get_ns() - *tsp;
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FACTOR
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// store as histogram
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STORE
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start.delete(&key);
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return 0;
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}
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int trace_req_done(struct pt_regs *ctx, struct request *req)
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{
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struct start_key key = {
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.dev = ddevt(req->__RQ_DISK__),
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.sector = req->__sector
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};
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SET_FLAGS
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return __trace_req_done(key);
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}
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int trace_req_done_tp(struct tp_args *args)
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{
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struct start_key key = {
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.dev = args->dev,
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.sector = args->sector
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};
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return __trace_req_done(key);
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}
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"""
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# code substitutions
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if args.milliseconds:
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bpf_text = bpf_text.replace('FACTOR', 'delta /= 1000000;')
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label = "msecs"
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else:
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bpf_text = bpf_text.replace('FACTOR', 'delta /= 1000;')
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label = "usecs"
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storage_str = ""
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store_str = ""
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if args.disks:
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storage_str += "BPF_HISTOGRAM(dist, disk_key_t);"
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disks_str = """
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disk_key_t dkey = {};
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dkey.dev = key.dev;
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dkey.slot = bpf_log2l(delta);
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dist.atomic_increment(dkey);
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"""
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store_str += disks_str
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elif args.flags:
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storage_str += "BPF_HISTOGRAM(dist, flag_key_t);"
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store_str += """
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flag_key_t fkey = {.slot = bpf_log2l(delta)};
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fkey.flags = key.flags;
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dist.atomic_increment(fkey);
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"""
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else:
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storage_str += "BPF_HISTOGRAM(dist);"
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store_str += "dist.atomic_increment(bpf_log2l(delta));"
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if args.disk is not None:
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disk_path = os.path.join('/dev', args.disk)
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if not os.path.exists(disk_path):
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print("no such disk '%s'" % args.disk)
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exit(1)
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stat_info = os.stat(disk_path)
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dev = os.major(stat_info.st_rdev) << 20 | os.minor(stat_info.st_rdev)
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disk_filter_str = """
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if(key.dev != %s) {
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return 0;
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}
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""" % (dev)
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bpf_text = bpf_text.replace('DISK_FILTER', disk_filter_str)
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else:
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bpf_text = bpf_text.replace('DISK_FILTER', '')
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if args.extension:
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storage_str += "BPF_ARRAY(extension, ext_val_t, 1);"
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store_str += """
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u32 index = 0;
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ext_val_t *ext_val = extension.lookup(&index);
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if (ext_val) {
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lock_xadd(&ext_val->total, delta);
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lock_xadd(&ext_val->count, 1);
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}
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"""
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bpf_text = bpf_text.replace("STORAGE", storage_str)
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bpf_text = bpf_text.replace("STORE", store_str)
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if BPF.kernel_struct_has_field(b'request', b'rq_disk') == 1:
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bpf_text = bpf_text.replace('__RQ_DISK__', 'rq_disk')
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else:
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bpf_text = bpf_text.replace('__RQ_DISK__', 'q->disk')
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if args.flags:
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bpf_text = bpf_text.replace('CMD_FLAGS', 'u64 flags;')
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bpf_text = bpf_text.replace('SET_FLAGS', 'key.flags = req->cmd_flags;')
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else:
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bpf_text = bpf_text.replace('CMD_FLAGS', '')
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bpf_text = bpf_text.replace('SET_FLAGS', '')
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if debug or args.ebpf:
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print(bpf_text)
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if args.ebpf:
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exit()
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# load BPF program
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b = BPF(text=bpf_text)
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if args.queued:
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if BPF.get_kprobe_functions(b'__blk_account_io_start'):
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b.attach_kprobe(event="__blk_account_io_start", fn_name="trace_req_start")
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elif BPF.get_kprobe_functions(b'blk_account_io_start'):
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b.attach_kprobe(event="blk_account_io_start", fn_name="trace_req_start")
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else:
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if args.flags:
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# Some flags are accessible in the rwbs field (RAHEAD, SYNC and META)
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# but other aren't. Disable the -F option for tracepoint for now.
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print("ERROR: blk_account_io_start probe not available. Can't use -F.")
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exit()
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b.attach_tracepoint(tp="block:block_io_start", fn_name="trace_req_start_tp")
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else:
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if BPF.get_kprobe_functions(b'blk_start_request'):
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b.attach_kprobe(event="blk_start_request", fn_name="trace_req_start")
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b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_req_start")
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if BPF.get_kprobe_functions(b'__blk_account_io_done'):
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b.attach_kprobe(event="__blk_account_io_done", fn_name="trace_req_done")
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elif BPF.get_kprobe_functions(b'blk_account_io_done'):
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b.attach_kprobe(event="blk_account_io_done", fn_name="trace_req_done")
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else:
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if args.flags:
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print("ERROR: blk_account_io_done probe not available. Can't use -F.")
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exit()
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b.attach_tracepoint(tp="block:block_io_done", fn_name="trace_req_done_tp")
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if not args.json:
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print("Tracing block device I/O... Hit Ctrl-C to end.")
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# cache disk major,minor -> diskname
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diskstats = "/proc/diskstats"
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disklookup = {}
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with open(diskstats) as stats:
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for line in stats:
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a = line.split()
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disklookup[a[0] + "," + a[1]] = a[2]
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def disk_print(d):
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major = d >> 20
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minor = d & ((1 << 20) - 1)
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disk = str(major) + "," + str(minor)
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if disk in disklookup:
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diskname = disklookup[disk]
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else:
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diskname = "?"
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return diskname
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# see blk_fill_rwbs():
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req_opf = {
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0: "Read",
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1: "Write",
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2: "Flush",
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3: "Discard",
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5: "SecureErase",
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6: "ZoneReset",
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7: "WriteSame",
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9: "WriteZeros"
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}
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REQ_OP_BITS = 8
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REQ_OP_MASK = ((1 << REQ_OP_BITS) - 1)
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REQ_SYNC = 1 << (REQ_OP_BITS + 3)
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REQ_META = 1 << (REQ_OP_BITS + 4)
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REQ_PRIO = 1 << (REQ_OP_BITS + 5)
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REQ_NOMERGE = 1 << (REQ_OP_BITS + 6)
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REQ_IDLE = 1 << (REQ_OP_BITS + 7)
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REQ_FUA = 1 << (REQ_OP_BITS + 9)
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REQ_RAHEAD = 1 << (REQ_OP_BITS + 11)
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REQ_BACKGROUND = 1 << (REQ_OP_BITS + 12)
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REQ_NOWAIT = 1 << (REQ_OP_BITS + 13)
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def flags_print(flags):
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desc = ""
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# operation
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if flags & REQ_OP_MASK in req_opf:
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desc = req_opf[flags & REQ_OP_MASK]
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else:
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desc = "Unknown"
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# flags
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if flags & REQ_SYNC:
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desc = "Sync-" + desc
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if flags & REQ_META:
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desc = "Metadata-" + desc
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if flags & REQ_FUA:
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desc = "ForcedUnitAccess-" + desc
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if flags & REQ_PRIO:
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desc = "Priority-" + desc
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if flags & REQ_NOMERGE:
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desc = "NoMerge-" + desc
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if flags & REQ_IDLE:
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desc = "Idle-" + desc
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if flags & REQ_RAHEAD:
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desc = "ReadAhead-" + desc
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if flags & REQ_BACKGROUND:
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desc = "Background-" + desc
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if flags & REQ_NOWAIT:
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desc = "NoWait-" + desc
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return desc
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# output
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exiting = 0 if args.interval else 1
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dist = b.get_table("dist")
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if args.extension:
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extension = b.get_table("extension")
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while (1):
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try:
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sleep(int(args.interval))
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except KeyboardInterrupt:
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exiting = 1
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print()
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if args.json:
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if args.timestamp:
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print("%-8s\n" % strftime("%H:%M:%S"), end="")
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if args.flags:
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dist.print_json_hist(label, "flags", flags_print)
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else:
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dist.print_json_hist(label, "disk", disk_print)
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else:
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if args.timestamp:
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print("%-8s\n" % strftime("%H:%M:%S"), end="")
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if args.flags:
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dist.print_log2_hist(label, "flags", flags_print)
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else:
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dist.print_log2_hist(label, "disk", disk_print)
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if args.extension:
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total = extension[0].total
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count = extension[0].count
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if count > 0:
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print("\navg = %ld %s, total: %ld %s, count: %ld\n" %
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(total / count, label, total, label, count))
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extension.clear()
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dist.clear()
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countdown -= 1
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if exiting or countdown == 0:
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exit()
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