Merge pull request #349 from brendangregg/master

biotop

README.md

@@ -67,6 +67,7 @@ Tools:
 
 - tools/[bashreadline](tools/bashreadline.py): Print entered bash commands system wide. [Examples](tools/bashreadline_example.txt).
 - tools/[biolatency](tools/biolatency.py): Summarize block device I/O latency as a histogram. [Examples](tools/biolatency_example.txt).
+- tools/[biotop](tools/biotop.py): Top for disks: Summarize block device I/O by process. [Examples](tools/biotop_example.txt).
 - tools/[biosnoop](tools/biosnoop.py): Trace block device I/O with PID and latency. [Examples](tools/biosnoop_example.txt).
 - tools/[bitesize](tools/bitesize.py): Show per process I/O size histogram. [Examples](tools/bitesize_example.txt).
 - tools/[cachestat](tools/cachestat.py): Trace page cache hit/miss ratio. [Examples](tools/cachestat_example.txt).

man/man8/biotop.8

+.TH biotop 8  "2016-02-06" "USER COMMANDS"
+.SH NAME
+biotop \- Block device (disk) I/O by process top.
+.SH SYNOPSIS
+.B biotop [\-h] [\-C] [\-r MAXROWS] [interval] [count]
+.SH DESCRIPTION
+This is top for disks. 
+
+This traces block device I/O (disk I/O), and prints a per-process summary every
+interval (by default, 1 second). The summary is sorted on the top disk
+consumers by throughput (Kbytes). The PID and process name shown are measured
+from when the I/O was first created, which usually identifies the responsible
+process.
+
+For efficiency, 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, and the final summary.
+
+This works by tracing various kernel blk_*() functions using dynamic tracing,
+and will need updating to match any changes to these functions.
+
+Since this uses BPF, only the root user can use this tool.
+.SH REQUIREMENTS
+CONFIG_BPF and bcc.
+.SH EXAMPLES
+.TP
+Summarize block device I/O by process, 1 second screen refresh:
+#
+.B biotop
+.TP
+Don't clear the screen:
+#
+.B biotop -C
+.TP
+5 second summaries, 10 times only:
+#
+.B biotop 5 10
+.SH FIELDS
+.TP
+loadavg:
+The contents of /proc/loadavg
+.TP
+PID
+Cached process ID, if present. This usually (but isn't guaranteed) to identify
+the responsible process for the I/O.
+.TP
+COMM
+Cached process name, if present. This usually (but isn't guaranteed) to identify
+the responsible process for the I/O.
+.TP
+D
+Direction: R == read, W == write.
+.TP
+MAJ
+Major device number.
+.TP
+MIN
+Minor device number.
+.TP
+DISK
+Disk device name.
+.TP
+I/O
+Number of I/O during the interval.
+.TP
+Kbytes
+Total Kbytes for these I/O, during the interval.
+.TP
+AVGms
+Average time for the I/O (latency) from the issue to the device, to its
+completion, in milliseconds.
+.SH OVERHEAD
+Since block device I/O usually has a relatively low frequency (< 10,000/s),
+the overhead for this tool is expected to be low or negligible. For high IOPS
+storage systems, test and quantify before use.
+.SH SOURCE
+This is from bcc.
+.IP
+https://github.com/iovisor/bcc
+.PP
+Also look in the bcc distribution for a companion _examples.txt file containing
+example usage, output, and commentary for this tool.
+.SH OS
+Linux
+.SH STABILITY
+Unstable - in development.
+.SH AUTHOR
+Brendan Gregg
+.SH SEE ALSO
+biosnoop(8), biolatency(8), iostat(1)

tools/biotop.py

+#!/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 type;
+    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;
+    info.type = req->cmd_flags & REQ_WRITE;
+    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,
+            "W" if k.type 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()

tools/biotop_example.txt

+Demonstrations of biotop, the Linux eBPF/bcc version.
+
+
+Short for block device I/O top, biotop summarizes which processes are
+performing disk I/O. It's top for disks. Sample output:
+
+# ./biotop
+Tracing... Output every 1 secs. Hit Ctrl-C to end
+
+08:04:11 loadavg: 1.48 0.87 0.45 1/287 14547
+
+PID    COMM             D MAJ MIN DISK       I/O  Kbytes  AVGms
+14501  cksum            R 202 1   xvda1      361   28832   3.39
+6961   dd               R 202 1   xvda1     1628   13024   0.59
+13855  dd               R 202 1   xvda1     1627   13016   0.59
+326    jbd2/xvda1-8     W 202 1   xvda1        3     168   3.00
+1880   supervise        W 202 1   xvda1        2       8   6.71
+1873   supervise        W 202 1   xvda1        2       8   2.51
+1871   supervise        W 202 1   xvda1        2       8   1.57
+1876   supervise        W 202 1   xvda1        2       8   1.22
+1892   supervise        W 202 1   xvda1        2       8   0.62
+1878   supervise        W 202 1   xvda1        2       8   0.78
+1886   supervise        W 202 1   xvda1        2       8   1.30
+1894   supervise        W 202 1   xvda1        2       8   3.46
+1869   supervise        W 202 1   xvda1        2       8   0.73
+1888   supervise        W 202 1   xvda1        2       8   1.48
+
+By default the screen refreshes every 1 second, and shows the top 20 disk
+consumers, sorted on total Kbytes. The first line printed is the header,
+which has the time and then the contents of /proc/loadavg.
+
+For the interval summarized by the output above, the "cksum" command performed
+361 disk reads to the "xvda1" device, for a total of 28832 Kbytes, with an
+average I/O time of 3.39 ms. Two "dd" processes were also reading from the
+same disk, which a higher I/O rate and lower latency. While the average I/O
+size is not printed, it can be determined by dividing the Kbytes column by
+the I/O column.
+
+The columns through to Kbytes show the workload applied. The final column,
+AVGms, shows resulting performance. Other bcc tools can be used to get more
+details when needed: biolatency and biosnoop.
+
+Many years ago I created the original "iotop", and later regretted not calling
+it diskiotop or blockiotop, as "io" alone is ambiguous. This time it is biotop.
+
+
+The -C option can be used to prevent the screen from clearing (my preference).
+Here's using it with a 5 second interval:
+
+# ./biotop -C 5
+Tracing... Output every 5 secs. Hit Ctrl-C to end
+
+08:09:44 loadavg: 0.42 0.44 0.39 2/282 22115
+
+PID    COMM             D MAJ MIN DISK       I/O  Kbytes  AVGms
+22069  dd               R 202 1   xvda1     5993   47976   0.33
+326    jbd2/xvda1-8     W 202 1   xvda1        3     168   2.67
+1866   svscan           R 202 1   xvda1       33     132   1.24
+1880   supervise        W 202 1   xvda1       10      40   0.56
+1873   supervise        W 202 1   xvda1       10      40   0.79
+1871   supervise        W 202 1   xvda1       10      40   0.78
+1876   supervise        W 202 1   xvda1       10      40   0.68
+1892   supervise        W 202 1   xvda1       10      40   0.71
+1878   supervise        W 202 1   xvda1       10      40   0.65
+1886   supervise        W 202 1   xvda1       10      40   0.78
+1894   supervise        W 202 1   xvda1       10      40   0.80
+1869   supervise        W 202 1   xvda1       10      40   0.91
+1888   supervise        W 202 1   xvda1       10      40   0.63
+22069  bash             R 202 1   xvda1        1      16  19.94
+9251   kworker/u16:2    W 202 16  xvdb         2       8   0.13
+
+08:09:49 loadavg: 0.47 0.44 0.39 1/282 22231
+
+PID    COMM             D MAJ MIN DISK       I/O  Kbytes  AVGms
+22069  dd               R 202 1   xvda1    13450  107600   0.35
+22199  cksum            R 202 1   xvda1      941   45548   4.63
+326    jbd2/xvda1-8     W 202 1   xvda1        3     168   2.93
+24467  kworker/0:2      W 202 16  xvdb         1      64   0.28
+1880   supervise        W 202 1   xvda1       10      40   0.81
+1873   supervise        W 202 1   xvda1       10      40   0.81
+1871   supervise        W 202 1   xvda1       10      40   1.03
+1876   supervise        W 202 1   xvda1       10      40   0.76
+1892   supervise        W 202 1   xvda1       10      40   0.74
+1878   supervise        W 202 1   xvda1       10      40   0.94
+1886   supervise        W 202 1   xvda1       10      40   0.76
+1894   supervise        W 202 1   xvda1       10      40   0.69
+1869   supervise        W 202 1   xvda1       10      40   0.72
+1888   supervise        W 202 1   xvda1       10      40   1.70
+22199  bash             R 202 1   xvda1        2      20   0.35
+482    xfsaild/md0      W 202 16  xvdb         5      13   0.27
+482    xfsaild/md0      W 202 32  xvdc         2       8   0.33
+31331  pickup           R 202 1   xvda1        1       4   0.31
+
+08:09:54 loadavg: 0.51 0.45 0.39 2/282 22346
+
+PID    COMM             D MAJ MIN DISK       I/O  Kbytes  AVGms
+22069  dd               R 202 1   xvda1    14689  117512   0.32
+326    jbd2/xvda1-8     W 202 1   xvda1        3     168   2.33
+1880   supervise        W 202 1   xvda1       10      40   0.65
+1873   supervise        W 202 1   xvda1       10      40   1.08
+1871   supervise        W 202 1   xvda1       10      40   0.66
+1876   supervise        W 202 1   xvda1       10      40   0.79
+1892   supervise        W 202 1   xvda1       10      40   0.67
+1878   supervise        W 202 1   xvda1       10      40   0.66
+1886   supervise        W 202 1   xvda1       10      40   1.02
+1894   supervise        W 202 1   xvda1       10      40   0.88
+1869   supervise        W 202 1   xvda1       10      40   0.89
+1888   supervise        W 202 1   xvda1       10      40   1.25
+
+08:09:59 loadavg: 0.55 0.46 0.40 2/282 22461
+
+PID    COMM             D MAJ MIN DISK       I/O  Kbytes  AVGms
+22069  dd               R 202 1   xvda1    14442  115536   0.33
+326    jbd2/xvda1-8     W 202 1   xvda1        3     168   3.46
+1880   supervise        W 202 1   xvda1       10      40   0.87
+1873   supervise        W 202 1   xvda1       10      40   0.87
+1871   supervise        W 202 1   xvda1       10      40   0.78
+1876   supervise        W 202 1   xvda1       10      40   0.86
+1892   supervise        W 202 1   xvda1       10      40   0.89
+1878   supervise        W 202 1   xvda1       10      40   0.87
+1886   supervise        W 202 1   xvda1       10      40   0.86
+1894   supervise        W 202 1   xvda1       10      40   1.06
+1869   supervise        W 202 1   xvda1       10      40   1.12
+1888   supervise        W 202 1   xvda1       10      40   0.98
+
+08:10:04 loadavg: 0.59 0.47 0.40 3/282 22576
+
+PID    COMM             D MAJ MIN DISK       I/O  Kbytes  AVGms
+22069  dd               R 202 1   xvda1    14179  113432   0.34
+326    jbd2/xvda1-8     W 202 1   xvda1        3     168   2.39
+1880   supervise        W 202 1   xvda1       10      40   0.81
+1873   supervise        W 202 1   xvda1       10      40   1.02
+1871   supervise        W 202 1   xvda1       10      40   1.15
+1876   supervise        W 202 1   xvda1       10      40   1.10
+1892   supervise        W 202 1   xvda1       10      40   0.77
+1878   supervise        W 202 1   xvda1       10      40   0.72
+1886   supervise        W 202 1   xvda1       10      40   0.81
+1894   supervise        W 202 1   xvda1       10      40   0.86
+1869   supervise        W 202 1   xvda1       10      40   0.83
+1888   supervise        W 202 1   xvda1       10      40   0.79
+24467  kworker/0:2      R 202 32  xvdc         3      12   0.26
+1056   cron             R 202 1   xvda1        2       8   0.30
+24467  kworker/0:2      R 202 16  xvdb         1       4   0.23
+
+08:10:09 loadavg: 0.54 0.46 0.40 2/281 22668
+
+PID    COMM             D MAJ MIN DISK       I/O  Kbytes  AVGms
+22069  dd               R 202 1   xvda1      250    2000   0.34
+326    jbd2/xvda1-8     W 202 1   xvda1        3     168   2.40
+1880   supervise        W 202 1   xvda1        8      32   0.93
+1873   supervise        W 202 1   xvda1        8      32   0.76
+1871   supervise        W 202 1   xvda1        8      32   0.60
+1876   supervise        W 202 1   xvda1        8      32   0.61
+1892   supervise        W 202 1   xvda1        8      32   0.68
+1878   supervise        W 202 1   xvda1        8      32   0.90
+1886   supervise        W 202 1   xvda1        8      32   0.57
+1894   supervise        W 202 1   xvda1        8      32   0.97
+1869   supervise        W 202 1   xvda1        8      32   0.69
+1888   supervise        W 202 1   xvda1        8      32   0.67
+
+This shows another "dd" command reading from xvda1. On this system, various
+"supervise" processes do 8 disk writes per second, every second (they are
+creating and updating "status" files).
+
+
+USAGE message:
+
+# ./biotop.py -h
+usage: biotop.py [-h] [-C] [-r MAXROWS] [interval] [count]
+
+Block device (disk) I/O by process
+
+positional arguments:
+  interval              output interval, in seconds
+  count                 number of outputs
+
+optional arguments:
+  -h, --help            show this help message and exit
+  -C, --noclear         don't clear the screen
+  -r MAXROWS, --maxrows MAXROWS
+                        maximum rows to print, default 20
+
+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