168 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright 2014, Michael Ellerman, IBM Corp.4 */5 6#define _GNU_SOURCE7 8#include <stdio.h>9#include <stdbool.h>10#include <string.h>11#include <sys/prctl.h>12 13#include "ebb.h"14 15 16/*17 * Run a calibrated instruction loop and count instructions executed using18 * EBBs. Make sure the counts look right.19 */20 21extern void thirty_two_instruction_loop(uint64_t loops);22 23static bool counters_frozen = true;24 25static int do_count_loop(struct event *event, uint64_t instructions,26 uint64_t overhead, bool report)27{28 int64_t difference, expected;29 double percentage;30 31 clear_ebb_stats();32 33 counters_frozen = false;34 mb();35 mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);36 37 thirty_two_instruction_loop(instructions >> 5);38 39 counters_frozen = true;40 mb();41 mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) | MMCR0_FC);42 43 count_pmc(4, sample_period);44 45 event->result.value = ebb_state.stats.pmc_count[4-1];46 expected = instructions + overhead;47 difference = event->result.value - expected;48 percentage = (double)difference / event->result.value * 100;49 50 if (report) {51 printf("Looped for %lu instructions, overhead %lu\n", instructions, overhead);52 printf("Expected %lu\n", expected);53 printf("Actual %llu\n", event->result.value);54 printf("Delta %ld, %f%%\n", difference, percentage);55 printf("Took %d EBBs\n", ebb_state.stats.ebb_count);56 }57 58 if (difference < 0)59 difference = -difference;60 61 /* Tolerate a difference of up to 0.0001 % */62 difference *= 10000 * 100;63 if (difference / event->result.value)64 return -1;65 66 return 0;67}68 69/* Count how many instructions it takes to do a null loop */70static uint64_t determine_overhead(struct event *event)71{72 uint64_t current, overhead;73 int i;74 75 do_count_loop(event, 0, 0, false);76 overhead = event->result.value;77 78 for (i = 0; i < 100; i++) {79 do_count_loop(event, 0, 0, false);80 current = event->result.value;81 if (current < overhead) {82 printf("Replacing overhead %lu with %lu\n", overhead, current);83 overhead = current;84 }85 }86 87 return overhead;88}89 90static void pmc4_ebb_callee(void)91{92 uint64_t val;93 94 val = mfspr(SPRN_BESCR);95 if (!(val & BESCR_PMEO)) {96 ebb_state.stats.spurious++;97 goto out;98 }99 100 ebb_state.stats.ebb_count++;101 count_pmc(4, sample_period);102out:103 if (counters_frozen)104 reset_ebb_with_clear_mask(MMCR0_PMAO);105 else106 reset_ebb();107}108 109int instruction_count(void)110{111 struct event event;112 uint64_t overhead;113 114 SKIP_IF(!ebb_is_supported());115 116 event_init_named(&event, 0x400FA, "PM_RUN_INST_CMPL");117 event_leader_ebb_init(&event);118 event.attr.exclude_kernel = 1;119 event.attr.exclude_hv = 1;120 event.attr.exclude_idle = 1;121 122 FAIL_IF(event_open(&event));123 FAIL_IF(ebb_event_enable(&event));124 125 sample_period = COUNTER_OVERFLOW;126 127 setup_ebb_handler(pmc4_ebb_callee);128 mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);129 ebb_global_enable();130 131 overhead = determine_overhead(&event);132 printf("Overhead of null loop: %lu instructions\n", overhead);133 134 /* Run for 1M instructions */135 FAIL_IF(do_count_loop(&event, 0x100000, overhead, true));136 137 /* Run for 10M instructions */138 FAIL_IF(do_count_loop(&event, 0xa00000, overhead, true));139 140 /* Run for 100M instructions */141 FAIL_IF(do_count_loop(&event, 0x6400000, overhead, true));142 143 /* Run for 1G instructions */144 FAIL_IF(do_count_loop(&event, 0x40000000, overhead, true));145 146 /* Run for 16G instructions */147 FAIL_IF(do_count_loop(&event, 0x400000000, overhead, true));148 149 /* Run for 64G instructions */150 FAIL_IF(do_count_loop(&event, 0x1000000000, overhead, true));151 152 /* Run for 128G instructions */153 FAIL_IF(do_count_loop(&event, 0x2000000000, overhead, true));154 155 ebb_global_disable();156 event_close(&event);157 158 printf("Finished OK\n");159 160 return 0;161}162 163int main(void)164{165 test_harness_set_timeout(300);166 return test_harness(instruction_count, "instruction_count");167}168