1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2014, Michael Ellerman, IBM Corp.
4 */
5
6 #define _GNU_SOURCE
7
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 using
18 * EBBs. Make sure the counts look right.
19 */
20
21 extern void thirty_two_instruction_loop(uint64_t loops);
22
23 static bool counters_frozen = true;
24
25 static 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 */
70 static 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
90 static 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);
102 out:
103 if (counters_frozen)
104 reset_ebb_with_clear_mask(MMCR0_PMAO);
105 else
106 reset_ebb();
107 }
108
109 int 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
163 int main(void)
164 {
165 test_harness_set_timeout(300);
166 return test_harness(instruction_count, "instruction_count");
167 }
168
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