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/* $OpenBSD: runqlat.bt,v 1.3 2022/05/01 20:23:11 bluhm Exp $ */
/*
* runqlat.bt Measure run queue latency (aka scheduler latency). OpenBSD.
*
* This measures the time from enqueue to on-cpu, for the same thread.
*
* WARNING: This traces scheduler functions, which can incur high overhead.
* This is not suitable for 24x7 monitoring.
*
* Copyright (c) 2014 Brendan Gregg. All rights reserved.
* Copyright (c) 2021 Martin Pieuchot. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* 19-Jun-2014 Brendan Gregg Created this.
* 08-Sep-2021 Martin Pieuchot Ported this to OpenBSD's btrace(8)
*/
/*
* Work around multiple enqueue/dequeue cycles due to priority changes
* before executing by registering only the first time a thread is put
* on a scheduler queue.
*/
tracepoint:sched:enqueue
/@ts[arg0] == 0/
{
/*
* For the enqueue and dequeue probes, arg0 is the thread ID.
*/
@ts[arg0] = nsecs
}
tracepoint:sched:on__cpu
/@ts[tid]/
{
$usec = (nsecs - @ts[tid]) / 1000;
@max_usec[0] = max($usec);
@dist_usec = hist($usec);
delete(@ts[tid]);
}
interval:hz:1
{
time("%H:%M:%S ");
printf("Run queue latency (us):\n");
print(@dist_usec);
printf("Max run queue latency: %d ms\n", @max_usec[0] / 1000);
clear(@dist_usec); clear(@max_usec);
}
END
{
clear(@ts);
time("%H:%M:%S ");
printf("Run queue latency (us):\n");
print(@dist_usec);
printf("Max run queue latency: %d ms\n", @max_usec[0] / 1000);
clear(@dist_usec); clear(@max_usec);
}
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