#!/usr/bin/env bpftrace

/*

* biostacks - Show disk I/O latency with initialization stacks.

*

* See BPF Performance Tools, Chapter 9, for an explanation of this tool.

*

* Copyright (c) 2019 Brendan Gregg.

* Licensed under the Apache License, Version 2.0 (the "License").

* This was originally created for the BPF Performance Tools book

* published by Addison Wesley. ISBN-13: 9780136554820

* When copying or porting, include this comment.

*

* 19-Mar-2019 Brendan Gregg Created this.

*/

config = { missing_probes = "ignore" }

BEGIN

{

printf("Tracing block I/O with init stacks. Hit Ctrl-C to end.\n");

}

kprobe:blk_account_io_start,

kprobe:__blk_account_io_start

{

@reqstack[arg0] = kstack;

@reqts[arg0] = nsecs;

}

kprobe:blk_start_request,

kprobe:blk_mq_start_request

/@reqts[arg0]/

{

@usecs[@reqstack[arg0]] = hist(nsecs - @reqts[arg0]);

delete(@reqstack[arg0]);

delete(@reqts[arg0]);

}

END

{

clear(@reqstack); clear(@reqts);

}