1/* $OpenBSD: runqlat.bt,v 1.3 2022/05/01 20:23:11 bluhm Exp $ */ 2 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 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 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 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 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 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 */ 44tracepoint: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 53tracepoint: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 62interval: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 71END 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} 80