filetop.8

README.md

@@ -74,6 +74,7 @@ Tools:
 - tools/[execsnoop](tools/execsnoop.py): Trace new processes via exec() syscalls. [Examples](tools/execsnoop_example.txt).
 - tools/[filelife](tools/filelife.py): Trace the lifespan of short-lived files. [Examples](tools/filelife_example.txt).
 - tools/[fileslower](tools/fileslower.py): Trace slow synchronous file reads and writes. [Examples](tools/fileslower_example.txt).
+- tools/[filetop](tools/filetop.py): File reads and writes by filename and process. Top for files. [Examples](tools/filetop_example.txt).
 - tools/[funccount](tools/funccount.py): Count kernel function calls. [Examples](tools/funccount_example.txt).
 - tools/[funclatency](tools/funclatency.py): Time kernel functions and show their latency distribution. [Examples](tools/funclatency_example.txt).
 - tools/[gethostlatency](tools/gethostlatency.py): Show latency for getaddrinfo/gethostbyname[2] calls. [Examples](tools/gethostlatency_example.txt).

man/man8/filetop.8

@@ -0,0 +1,110 @@
+.TH filetop 8 "2016-02-08" "USER COMMANDS"
+.SH NAME
+filetop \- File reads and writes by filename and process. Top for files.
+.SH SYNOPSIS
+.B filetop [\-h] [\-C] [\-r MAXROWS] [\-p PID] [interval] [count]
+.SH DESCRIPTION
+This is top for files. 
+
+This traces file reads and writes, and prints a per-file summary every
+interval (by default, 1 second). The summary is sorted on the highest read
+throughput (Kbytes).
+
+This uses in-kernel eBPF maps to store per process summaries for efficiency.
+
+This script works by tracing the __vfs_read() and __vfs_write() functions using
+kernel dynamic tracing, which instruments explicit read and write calls. If
+files are read or written using another means (eg, via mmap()), then they
+will not be visible using this tool. Also, this tool will need updating to
+match any code changes to those vfs functions.
+
+This should be useful for file system workload characterization when analyzing
+the performance of applications.
+
+Note that tracing VFS level reads and writes can be a frequent activity, and
+this tool can begin to cost measurable overhead at high I/O rates.
+
+Since this uses BPF, only the root user can use this tool.
+.SH REQUIREMENTS
+CONFIG_BPF and bcc.
+.SH OPTIONS
+.TP
+\-C
+Don't clear the screen.
+.TP
+\-r MAXROWS
+Maximum number of rows to print. Default is 20.
+.TP
+\-p PID
+Trace this PID only.
+.TP
+interval
+Interval between updates, seconds.
+.TP
+count
+Number of interval summaries.
+
+.SH EXAMPLES
+.TP
+Summarize block device I/O by process, 1 second screen refresh:
+#
+.B filetop
+.TP
+Don't clear the screen, and top 8 rows only:
+#
+.B filetop -Cr 8
+.TP
+5 second summaries, 10 times only:
+#
+.B filetop 5 10
+.SH FIELDS
+.TP
+loadavg:
+The contents of /proc/loadavg
+.TP
+PID
+Process ID.
+.TP
+COMM
+Process name.
+.TP
+READS
+Count of reads during interval.
+.TP
+WRITES
+Count of writes during interval.
+.TP
+R_Kb
+Total read Kbytes during interval.
+.TP
+W_Kb
+Total write Kbytes during interval.
+.TP
+T
+Type of file: R == regular, S == socket, O == other (pipe, etc).
+.SH OVERHEAD
+Depending on the frequency of application reads and writes, overhead can become
+significant, in the worst case slowing applications by over 50%. Hopefully for
+real world workloads the overhead is much less -- test before use. The reason
+for the high overhead is that VFS reads and writes can be a frequent event, and
+despite the eBPF overhead being very small per event, if you multiply this
+small overhead by a million events per second, it becomes a million times
+worse. Literally. You can gauge the number of reads and writes using the
+vfsstat(8) tool, also from bcc.
+.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 INSPIRATION
+top(1) by William LeFebvre
+.SH SEE ALSO
+vfsstat(8), vfscount(8), fileslower(8)

tools/filetop.py

@@ -0,0 +1,188 @@
+#!/usr/bin/python
+# @lint-avoid-python-3-compatibility-imports
+#
+# filetop file reads and writes by process.
+# For Linux, uses BCC, eBPF.
+#
+# USAGE: filetop.py [-h] [-C] [-r MAXROWS] [interval] [count]
+#
+# This uses in-kernel eBPF maps to store per process summaries for efficiency.
+#
+# 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:
+ ./filetop # file I/O top, 1 second refresh
+ ./filetop -C # don't clear the screen
+ ./filetop -p 181 # PID 181 only
+ ./filetop 5 # 5 second summaries
+ ./filetop 5 10 # 5 second summaries, 10 times only
+"""
+parser = argparse.ArgumentParser(
+ description="File reads and writes 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("-p", "--pid",
+ help="trace this PID only")
+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)
+debug = 0
+
+# linux stats
+loadavg = "/proc/loadavg"
+
+# signal handler
+def signal_ignore(signal, frame):
+ print()
+
+# define BPF program
+bpf_text = """
+#include <uapi/linux/ptrace.h>
+#include <linux/blkdev.h>
+
+#define MAX_FILE_LEN 32
+
+// the key for the output summary
+struct info_t {
+ u32 pid;
+ char name[TASK_COMM_LEN];
+ char file[MAX_FILE_LEN];
+ char type;
+};
+
+// the value of the output summary
+struct val_t {
+ u64 reads;
+ u64 writes;
+ u64 rbytes;
+ u64 wbytes;
+};
+
+BPF_HASH(counts, struct info_t, struct val_t);
+
+static int do_entry(struct pt_regs *ctx, struct file *file,
+ char __user *buf, size_t count, int is_read)
+{
+ u32 pid;
+
+ pid = bpf_get_current_pid_tgid();
+ if (FILTER)
+ return 0;
+
+ // skip I/O lacking a filename
+ struct dentry *de = file->f_path.dentry;
+ if (de->d_iname[0] == 0)
+ return 0;
+
+ // store counts and sizes by pid & file
+ struct info_t info = {.pid = pid};
+ bpf_get_current_comm(&info.name, sizeof(info.name));
+ __builtin_memcpy(&info.file, de->d_iname, sizeof(info.file));
+ int mode = file->f_inode->i_mode;
+ if (S_ISREG(mode)) {
+ info.type = 'R';
+ } else if (S_ISSOCK(mode)) {
+ info.type = 'S';
+ } else {
+ info.type = 'O';
+ }
+
+ struct val_t *valp, zero = {};
+ valp = counts.lookup_or_init(&info, &zero);
+ if (is_read) {
+ valp->reads++;
+ valp->rbytes += count;
+ } else {
+ valp->writes++;
+ valp->wbytes += count;
+ }
+
+ return 0;
+}
+
+int trace_read_entry(struct pt_regs *ctx, struct file *file,
+ char __user *buf, size_t count)
+{
+ return do_entry(ctx, file, buf, count, 1);
+}
+
+int trace_write_entry(struct pt_regs *ctx, struct file *file,
+ char __user *buf, size_t count)
+{
+ return do_entry(ctx, file, buf, count, 0);
+}
+
+"""
+if args.pid:
+ bpf_text = bpf_text.replace('FILTER', 'pid != %s' % args.pid)
+else:
+ bpf_text = bpf_text.replace('FILTER', '0')
+if debug:
+ print(bpf_text)
+
+# initialize BPF
+b = BPF(text=bpf_text)
+b.attach_kprobe(event="__vfs_read", fn_name="trace_read_entry")
+b.attach_kprobe(event="__vfs_write", fn_name="trace_write_entry")
+
+print('Tracing... Output every %d secs. Hit Ctrl-C to end' % interval)
+
+# 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 %-6s %-6s %-7s %-7s %1s %s" % ("PID", "COMM",
+ "READS", "WRITES", "R_Kb", "W_Kb", "T", "FILE"))
+
+ # by-PID output
+ counts = b.get_table("counts")
+ line = 0
+ for k, v in reversed(sorted(counts.items(),
+ key=lambda counts: counts[1].rbytes)):
+
+ # print line
+ print("%-6d %-16s %-6d %-6d %-7d %-7d %1s %s" % (k.pid, k.name,
+ v.reads, v.writes, v.rbytes / 1024, v.wbytes / 1024, k.type,
+ k.file))
+
+ line += 1
+ if line >= maxrows:
+ break
+ counts.clear()
+
+ countdown -= 1
+ if exiting or countdown == 0:
+ print("Detaching...")
+ exit()