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Annotation of src/share/btrace/runqlat.bt, Revision 1.1

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