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(loops: instructions >> 5); |
38 | |
39 | counters_frozen = true; |
40 | mb(); |
41 | mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) | MMCR0_FC); |
42 | |
43 | count_pmc(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, instructions: 0, overhead: 0, report: false); |
76 | overhead = event->result.value; |
77 | |
78 | for (i = 0; i < 100; i++) { |
79 | do_count_loop(event, instructions: 0, overhead: 0, report: 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(pmc: 4, sample_period); |
102 | out: |
103 | if (counters_frozen) |
104 | reset_ebb_with_clear_mask(mmcr0_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(e: &event, config: 0x400FA, name: "PM_RUN_INST_CMPL" ); |
117 | event_leader_ebb_init(e: &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(e: &event)); |
123 | FAIL_IF(ebb_event_enable(e: &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: &event); |
132 | printf("Overhead of null loop: %lu instructions\n" , overhead); |
133 | |
134 | /* Run for 1M instructions */ |
135 | FAIL_IF(do_count_loop(event: &event, instructions: 0x100000, overhead, report: true)); |
136 | |
137 | /* Run for 10M instructions */ |
138 | FAIL_IF(do_count_loop(event: &event, instructions: 0xa00000, overhead, report: true)); |
139 | |
140 | /* Run for 100M instructions */ |
141 | FAIL_IF(do_count_loop(event: &event, instructions: 0x6400000, overhead, report: true)); |
142 | |
143 | /* Run for 1G instructions */ |
144 | FAIL_IF(do_count_loop(event: &event, instructions: 0x40000000, overhead, report: true)); |
145 | |
146 | /* Run for 16G instructions */ |
147 | FAIL_IF(do_count_loop(event: &event, instructions: 0x400000000, overhead, report: true)); |
148 | |
149 | /* Run for 64G instructions */ |
150 | FAIL_IF(do_count_loop(event: &event, instructions: 0x1000000000, overhead, report: true)); |
151 | |
152 | /* Run for 128G instructions */ |
153 | FAIL_IF(do_count_loop(event: &event, instructions: 0x2000000000, overhead, report: true)); |
154 | |
155 | ebb_global_disable(); |
156 | event_close(e: &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 | |