/usr/share/systemtap/examples/lwtools
Edit: /usr/share/systemtap/examples/lwtools/biolatency-nd.stp (2071B)
#!/usr/bin/stap
/*
* biolatency-nd.stp Measure storage (bio) latency distribution.
* For Linux, uses SystemTap (non-debuginfo).
*
* USAGE: ./biolatency-nd.stp [interval [count]]
*
* This script uses the kernel tracepoints block_rq_issue and block_rq_complete,
* to trace the time from storage request to completion. To include extra time
* spent queued in the kernel, change block_rq_issue to block_rq_insert.
*
* From systemtap-lwtools: https://github.com/brendangregg/systemtap-lwtools
*
* See the corresponding man page (in systemtap-lwtools) for more info.
*
* Copyright (C) 2015 Brendan Gregg.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* 01-Feb-2015 Brendan Gregg Created this.
*/
global ts[65536]; # 65536 is max concurrent I/O
global lat, interval = 0, secs = 0, count = 0, output = 0;
probe begin
{
printf("Tracing block I/O... ");
if (argv_1 != "") {
interval = strtol(argv_1, 10);
if (argv_2 != "") {
count = strtol(argv_2, 10);
}
printf("Output every %d secs.\n", interval);
} else {
printf("Hit Ctrl-C to end.\n");
}
}
probe kernel.trace("block_rq_issue") {
ts[$rq] = gettimeofday_ns();
}
probe kernel.trace("block_rq_complete") {
if (ts[$rq]) {
lat <<< gettimeofday_ns() - ts[$rq];
delete ts[$rq];
}
}
function print_report()
{
printf("\nbio latency (ns):\n");
if (@count(lat)) { print(@hist_log(lat)); }
delete lat;
}
probe timer.s(1)
{
if (interval) {
if (++secs == interval) {
print_report();
secs = 0;
count && (++output == count) && exit();
}
}
}
probe end
{
!interval && print_report();
delete secs;
delete output;
}