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Annotation of src/share/btrace/runqlat.bt, Revision 1.3

1.3     ! bluhm       1: /*     $OpenBSD$       */
        !             2:
1.1       mpi         3: /*
                      4:  * runqlat.bt  Measure run queue latency (aka scheduler latency). OpenBSD.
                      5:  *
                      6:  * This measures the time from enqueue to on-cpu, for the same thread.
                      7:  *
                      8:  * WARNING: This traces scheduler functions, which can incur high overhead.
                      9:  * This is not suitable for 24x7 monitoring.
                     10:  *
                     11:  * Copyright (c) 2014 Brendan Gregg. All rights reserved.
                     12:  * Copyright (c) 2021 Martin Pieuchot. All rights reserved.
                     13:  *
1.2       mpi        14:  * Redistribution and use in source and binary forms, with or without
1.1       mpi        15:  * modification, are permitted provided that the following conditions
                     16:  * are met:
1.2       mpi        17:  * 1. Redistributions of source code must retain the above copyright
1.1       mpi        18:  *    notice, this list of conditions and the following disclaimer.
1.2       mpi        19:  * 2. Redistributions in binary form must reproduce the above copyright
1.1       mpi        20:  *    notice, this list of conditions and the following disclaimer in the
                     21:  *    documentation and/or other materials provided with the distribution.
                     22:  *
                     23:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
                     24:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     25:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     26:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
                     27:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     28:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
1.2       mpi        29:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     30:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
1.1       mpi        31:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
1.2       mpi        32:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
1.1       mpi        33:  * SUCH DAMAGE.
                     34:  *
                     35:  * 19-Jun-2014 Brendan Gregg   Created this.
                     36:  * 08-Sep-2021 Martin Pieuchot Ported this to OpenBSD's btrace(8)
                     37:  */
                     38:
                     39: /*
                     40:  * Work around multiple enqueue/dequeue cycles due to priority changes
                     41:  * before executing by registering only the first time a thread is put
                     42:  * on a scheduler queue.
                     43:  */
                     44: tracepoint:sched:enqueue
                     45: /@ts[arg0] == 0/
                     46: {
                     47:        /*
                     48:         * For the enqueue and dequeue probes, arg0 is the thread ID.
                     49:         */
                     50:        @ts[arg0] = nsecs
                     51: }
                     52:
                     53: tracepoint:sched:on__cpu
                     54: /@ts[tid]/
                     55: {
                     56:        $usec = (nsecs - @ts[tid]) / 1000;
                     57:        @max_usec[0] = max($usec);
                     58:        @dist_usec = hist($usec);
                     59:        delete(@ts[tid]);
                     60: }
                     61:
                     62: interval:hz:1
                     63: {
                     64:        time("%H:%M:%S  ");
                     65:        printf("Run queue latency (us):\n");
                     66:        print(@dist_usec);
                     67:        printf("Max run queue latency: %d ms\n", @max_usec[0] / 1000);
                     68:        clear(@dist_usec); clear(@max_usec);
                     69: }
                     70:
                     71: END
                     72: {
                     73:        clear(@ts);
                     74:        time("%H:%M:%S  ");
                     75:        printf("Run queue latency (us):\n");
                     76:        print(@dist_usec);
                     77:        printf("Max run queue latency: %d ms\n", @max_usec[0] / 1000);
                     78:        clear(@dist_usec); clear(@max_usec);
                     79: }