1 /*
2 * Copyright (c) Meta Platforms, Inc. and affiliates.
3 * All rights reserved.
4 *
5 * This source code is licensed under the BSD-style license found in the
6 * LICENSE file in the root directory of this source tree.
7 */
8
9 #include <executorch/extension/threadpool/cpuinfo_utils.h>
10
11 #include <fstream>
12 #include <mutex>
13 #include <string>
14 #include <vector>
15
16 #include <executorch/runtime/platform/assert.h>
17
18 namespace executorch::extension::cpuinfo {
19
20 // Ignore revisions (last digit (4 LSBs))
21 #define CPUINFO_ARM_MIDR_CORTEX_A520 UINT32_C(0x410FD800)
22 #define CPUINFO_ARM_MIDR_CORTEX_A53 UINT32_C(0x410FD030)
23 #define CPUINFO_ARM_MIDR_CORTEX_A55 UINT32_C(0x410FD050)
24 #define CPUINFO_ARM_MIDR_CORTEX_A57 UINT32_C(0x410FD070)
25
26 #define RIVISION_MASK UINT32_C(0xFFFFFFF0)
27
28 namespace {
is_non_performant_core(const struct cpuinfo_uarch_info * uarch_info)29 bool is_non_performant_core(const struct cpuinfo_uarch_info* uarch_info) {
30 switch (uarch_info->uarch) {
31 case cpuinfo_uarch_cortex_a55:
32 case cpuinfo_uarch_cortex_a53:
33 case cpuinfo_uarch_cortex_a510:
34 case cpuinfo_uarch_icestorm:
35 return true;
36 // This can be so many other cores.
37 // Need to update this to better account for slow cores
38 // Also does not account Apple's A/M series cores
39 // And not yet qcomm's
40 default:
41 break;
42 }
43 // A520 is not yet updated in cpuinfo
44 // Hence decode it separately.
45 #if CPUINFO_ARCH_ARM || CPUINFO_ARCH_ARM64
46 if ((uarch_info->midr & RIVISION_MASK) == CPUINFO_ARM_MIDR_CORTEX_A520) {
47 return true;
48 }
49 #endif
50 return false;
51 }
52
get_static_cpu_midr_vector()53 std::vector<uint32_t>* get_static_cpu_midr_vector() {
54 static std::vector<uint32_t> cpu_midrs;
55 return &cpu_midrs;
56 }
57
_get_model_specific_num_cores()58 uint32_t _get_model_specific_num_cores() {
59 // Not sure how reliable this is but going with it for now.
60 const std::string kImageVersionPath = "/sys/devices/soc0/image_version";
61 ET_LOG(Info, "Reading file %s", kImageVersionPath.c_str());
62 std::fstream image_version_file(kImageVersionPath, std::ios_base::in);
63 if (image_version_file.is_open()) {
64 std::string x;
65 std::getline(image_version_file, x);
66 // Hardcoding some rules for now
67 if (x.find("S911") != std::string::npos) {
68 // Samsung S23 has:
69 // 1x3.36 GHz Cortex-X3
70 // 2x2.8 GHz Cortex-A715
71 // 2x2.8 GHz Cortex-A710
72 // 3x2.0 GHz Cortex-A510
73 // And we have balanced execution with 4 cores.
74 return 4;
75 }
76 }
77 ET_LOG(Info, "Failed to open midr file %s", kImageVersionPath.c_str());
78 return 0;
79 }
80
populate_available_cpu_mids()81 bool populate_available_cpu_mids() {
82 std::vector<uint32_t>* cpu_midrs = get_static_cpu_midr_vector();
83 uint32_t num_possible_cores = cpuinfo_get_processors_count();
84 cpu_midrs->resize(num_possible_cores);
85 const std::string kMidrFilePathPrefix = "/sys/devices/system/cpu/cpu";
86 const std::string kMidrFilePathSuffix = "/regs/identification/midr_el1";
87 for (int32_t i = 0; i < num_possible_cores; ++i) {
88 std::string midr_file_path =
89 kMidrFilePathPrefix + std::to_string(i) + kMidrFilePathSuffix;
90 ET_LOG(Info, "Reading file %s", midr_file_path.c_str());
91 std::fstream midr_file(midr_file_path, std::ios_base::in);
92 uint32_t tmp{0};
93 if (midr_file.is_open()) {
94 std::string x;
95 std::getline(midr_file, x);
96 tmp = std::stoi(x, nullptr, 16);
97 (*cpu_midrs)[i] = tmp;
98 } else {
99 ET_LOG(Info, "Failed to open midr file %s", midr_file_path.c_str());
100 cpu_midrs->clear();
101 return false;
102 }
103 }
104 return true;
105 }
106
_get_num_performant_cores()107 uint32_t _get_num_performant_cores() {
108 // @lint-ignore CLANGTIDY facebook-hte-std::once_flag
109 static std::once_flag flag;
110 // @lint-ignore CLANGTIDY facebook-hte-std::call_once
111 std::call_once(flag, []() { populate_available_cpu_mids(); });
112 std::vector<uint32_t>* cpu_midrs = get_static_cpu_midr_vector();
113 uint32_t num_possible_cores = cpuinfo_get_processors_count();
114 if (num_possible_cores != cpu_midrs->size()) {
115 ET_LOG(Info, "CPU info and manual query on # of cpus dont match.");
116 return 0;
117 }
118 for (int32_t i = 0; i < cpu_midrs->size(); ++i) {
119 uint32_t masked_midr = (*cpu_midrs)[i] & RIVISION_MASK;
120 switch (masked_midr) {
121 case CPUINFO_ARM_MIDR_CORTEX_A520:
122 case CPUINFO_ARM_MIDR_CORTEX_A53:
123 case CPUINFO_ARM_MIDR_CORTEX_A55:
124 case CPUINFO_ARM_MIDR_CORTEX_A57:
125 num_possible_cores--;
126 break;
127 default:
128 break;
129 }
130 }
131 return num_possible_cores;
132 }
133
134 } // namespace
135
get_num_performant_cores()136 uint32_t get_num_performant_cores() {
137 ET_CHECK_MSG(cpuinfo_initialize(), "cpuinfo cannot be initialized.");
138 // First try and see if we have number of cores profiled for this specific
139 // device
140 uint32_t model_specific_num_cores = _get_model_specific_num_cores();
141 if (model_specific_num_cores > 0) {
142 return model_specific_num_cores;
143 }
144
145 // Else looks at either the # of litte cores if found
146 // Or parse the midr in "Something seems wrong" section.
147 const uint32_t uarch_count = cpuinfo_get_uarchs_count();
148 uint32_t num_possible_cores = cpuinfo_get_processors_count();
149 uint32_t num_non_performant_core = 0;
150 if (uarch_count > 1) {
151 for (int32_t i = 0; i < uarch_count; ++i) {
152 const struct cpuinfo_uarch_info* uarch_info = cpuinfo_get_uarch(i);
153 if (is_non_performant_core(uarch_info)) {
154 num_non_performant_core += uarch_info->processor_count;
155 }
156 }
157 ET_LOG(Info, "Number of efficient cores %d", num_non_performant_core);
158 if (num_possible_cores <= num_non_performant_core) {
159 ET_LOG(
160 Info, "Total number of cores must be larger than efficient cores.");
161 return 0;
162 }
163 return (num_possible_cores - num_non_performant_core);
164 } else {
165 // Something seems wrong. Lets check each processor's midr
166 // In one plua 12 while it has 2 little cores, the topology
167 // reported in /sys/devices/system/cpu/cpu* /topology/core_siblings_list
168 // report wrong topology which results in wront configratuon
169 return _get_num_performant_cores();
170 }
171 }
172
173 } // namespace executorch::extension::cpuinfo
174