Add bitesize tool

man/man8/bitesize.8

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+.TH bitesize 8 "2016-02-05" "USER COMMANDS"
+.SH NAME
+bitesize \- Summarize block device I/O size as a histogram \- Linux eBPF/bcc.
+.SH SYNOPSIS
+.B bitesize
+.SH DESCRIPTION
+Show I/O distribution for requested block sizes, by process name.
+
+This works by tracing block I/O kernel functions using dynamic
+tracing and prints a historgram of I/O size.
+
+Since this uses BPF, only the root user can use this tool.
+.SH REQUIREMENTS
+CONFIG_BPF and bcc.
+.SH EXAMPLES
+.TP
+Count I/O size per process until Ctrl-C is hit:
+#
+.B bitesize
+.SH FIELDS
+.TP
+Kbtes
+Size in kilobytes of range
+.TP
+count
+How many I/O fell into this range
+.TP
+distribution
+An ASCII bar chart to visualize the distribution (count column)
+
+.SH OVERHEAD
+This traces kernel block I/O functions to update a histgroam, which are
+asynchronously copied to user-space. This method is very efficient, and 
+the overhead for most storage I/O rates (< 10k IOPS) should be negligible. 
+If you have a higher IOPS storage environment, test and quantify the overhead 
+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
+Allan McAleavy
+.SH SEE ALSO
+https://github.com/brendangregg/systemtap-lwtools/blob/master/disk/bitesize-nd.stp

tools/bitesize.py

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+#!/usr/bin/python
+#
+# bitehist.py Block I/O size histogram.
+# For Linux, uses BCC, eBPF. See .c file.
+#
+# USAGE: bitesize
+# Ctrl-C will print the partially gathered histogram then exit.
+#
+#
+# Copyright (c) 2016 Allan McAleavy
+# Licensed under the Apache License, Version 2.0 (the "License")
+#
+# 05-Feb-2016 Allan McAleavy ran pep8 against file
+
+from bcc import BPF
+from time import sleep
+
+bpf_text = """
+#include <uapi/linux/ptrace.h>
+#include <linux/blkdev.h>
+
+struct proc_key_t {
+ char name[TASK_COMM_LEN];
+ u64 slot;
+};
+
+struct val_t {
+ char name[TASK_COMM_LEN];
+};
+
+BPF_HISTOGRAM(dist, struct proc_key_t);
+BPF_HASH(commbyreq, struct request *, struct val_t);
+
+int trace_pid_start(struct pt_regs *ctx, struct request *req)
+{
+ struct val_t val = {};
+
+ if (bpf_get_current_comm(&val.name, sizeof(val.name)) == 0) {
+ commbyreq.update(&req, &val);
+ }
+ return 0;
+}
+
+int do_count (struct pt_regs *ctx, struct request *req)
+{
+ struct val_t *valp;
+
+ valp = commbyreq.lookup(&req);
+ if ( valp == 0) {
+ return 0;
+ }
+
+ if (req->__data_len > 0) {
+ struct proc_key_t key = {.slot = bpf_log2l(req->__data_len / 1024)};
+ bpf_probe_read(&key.name, sizeof(key.name),valp->name);
+ dist.increment(key);
+ }
+ return 0;
+}
+"""
+
+# load BPF program
+b = BPF(text=bpf_text)
+b.attach_kprobe(event="blk_account_io_start", fn_name="trace_pid_start")
+b.attach_kprobe(event="blk_account_io_completion", fn_name="do_count")
+
+print("Tracing... Hit Ctrl-C to end.")
+
+# trace until Ctrl-C
+dist = b.get_table("dist")
+
+try:
+ sleep(99999999)
+except KeyboardInterrupt:
+ dist.print_log2_hist("Kbytes", "Process Name:")

tools/bitesize_example.txt

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+Example of BCC tool bitesize.py
+
+The aim of this tool is to show I/O distribution for requested block sizes, by process name.
+
+# ./bitesize.py
+Tracing... Hit Ctrl-C to end.
+^C
+
+Process Name: = 'kworker/u128:1'
+ Kbytes : count distribution
+ 0 -> 1 : 1 |******************** |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 2 |****************************************|
+
+Process Name: = 'bitesize.py'
+ Kbytes : count distribution
+ 0 -> 1 : 0 | |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 0 | |
+ 8 -> 15 : 0 | |
+ 16 -> 31 : 0 | |
+ 32 -> 63 : 0 | |
+ 64 -> 127 : 0 | |
+ 128 -> 255 : 1 |****************************************|
+
+Process Name: = 'dd'
+ Kbytes : count distribution
+ 0 -> 1 : 3 | |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 6 | |
+ 8 -> 15 : 0 | |
+ 16 -> 31 : 1 | |
+ 32 -> 63 : 1 | |
+ 64 -> 127 : 0 | |
+ 128 -> 255 : 0 | |
+ 256 -> 511 : 1 | |
+ 512 -> 1023 : 0 | |
+ 1024 -> 2047 : 488 |****************************************|
+
+Process Name: = 'jbd2/dm-1-8'
+ Kbytes : count distribution
+ 0 -> 1 : 0 | |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 1 |****************************************|
+
+Process Name: = 'cat'
+ Kbytes : count distribution
+ 0 -> 1 : 1 | |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 0 | |
+ 8 -> 15 : 0 | |
+ 16 -> 31 : 0 | |
+ 32 -> 63 : 1 | |
+ 64 -> 127 : 0 | |
+ 128 -> 255 : 0 | |
+ 256 -> 511 : 1924 |****************************************|
+
+Process Name: = 'ntpd'
+ Kbytes : count distribution
+ 0 -> 1 : 0 | |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 104 |****************************************|
+
+Process Name: = 'vmtoolsd'
+ Kbytes : count distribution
+ 0 -> 1 : 0 | |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 1 |****************************************|
+
+Process Name: = 'bash'
+ Kbytes : count distribution
+ 0 -> 1 : 0 | |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 0 | |
+ 8 -> 15 : 0 | |
+ 16 -> 31 : 2 |****************************************|
+
+Process Name: = 'jbd2/sdb-8'
+ Kbytes : count distribution
+ 0 -> 1 : 0 | |
+ 2 -> 3 : 0 | |
+ 4 -> 7 : 1 |****************************************|
+ 8 -> 15 : 0 | |
+ 16 -> 31 : 0 | |
+ 32 -> 63 : 1 |****************************************|
+
+We can see from above that there was a dd command being run which generated 488 IOPS between 1MB and 2MB, we can also see the
+cat command generating 1924 IOPS between 256Kb and 512Kb.
+
+
+See also systemtap version:
+https://github.com/brendangregg/systemtap-lwtools/blob/master/disk/bitesize-nd.stp