in src/arm/linux/clusters.c [56:287]
bool cpuinfo_arm_linux_detect_core_clusters_by_heuristic(
uint32_t usable_processors,
uint32_t max_processors,
struct cpuinfo_arm_linux_processor processors[restrict static max_processors])
{
uint32_t cluster_processors[3];
switch (usable_processors) {
case 10:
cluster_processors[0] = 4;
cluster_processors[1] = 4;
cluster_processors[2] = 2;
break;
case 8:
cluster_processors[0] = 4;
cluster_processors[1] = 4;
break;
case 6:
cluster_processors[0] = 4;
cluster_processors[1] = 2;
break;
#if defined(__ANDROID__) && CPUINFO_ARCH_ARM
case 5:
/*
* The only processor with 5 cores is Leadcore L1860C (ARMv7, mobile),
* but this configuration is not too unreasonable for a virtualized ARM server.
*/
cluster_processors[0] = 4;
cluster_processors[1] = 1;
break;
#endif
default:
return false;
}
/*
* Assignment of processors to core clusters is done in two passes:
* 1. Verify that the clusters proposed by heuristic are compatible with known details about processors.
* 2. If verification passed, update core clusters for the processors.
*/
uint32_t cluster = 0;
uint32_t expected_cluster_processors = 0;
uint32_t cluster_start, cluster_flags, cluster_midr, cluster_max_frequency, cluster_min_frequency;
bool expected_cluster_exists;
for (uint32_t i = 0; i < max_processors; i++) {
if (bitmask_all(processors[i].flags, CPUINFO_LINUX_FLAG_VALID)) {
if (expected_cluster_processors == 0) {
/* Expect this processor to start a new cluster */
expected_cluster_exists = !!(processors[i].flags & CPUINFO_LINUX_FLAG_PACKAGE_CLUSTER);
if (expected_cluster_exists) {
if (processors[i].package_leader_id != i) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"processor %"PRIu32" is expected to start a new cluster #%"PRIu32" with %"PRIu32" cores, "
"but system siblings lists reported it as a sibling of processor %"PRIu32,
i, cluster, cluster_processors[cluster], processors[i].package_leader_id);
return false;
}
} else {
cluster_flags = 0;
}
cluster_start = i;
expected_cluster_processors = cluster_processors[cluster++];
} else {
/* Expect this processor to belong to the same cluster as processor */
if (expected_cluster_exists) {
/*
* The cluster suggested by the heuristic was already parsed from system siblings lists.
* For all processors we expect in the cluster, check that:
* - They have pre-assigned cluster from siblings lists (CPUINFO_LINUX_FLAG_PACKAGE_CLUSTER flag).
* - They were assigned to the same cluster based on siblings lists
* (package_leader_id points to the first processor in the cluster).
*/
if ((processors[i].flags & CPUINFO_LINUX_FLAG_PACKAGE_CLUSTER) == 0) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"processor %"PRIu32" is expected to belong to the cluster of processor %"PRIu32", "
"but system siblings lists did not report it as a sibling of processor %"PRIu32,
i, cluster_start, cluster_start);
return false;
}
if (processors[i].package_leader_id != cluster_start) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"processor %"PRIu32" is expected to belong to the cluster of processor %"PRIu32", "
"but system siblings lists reported it to belong to the cluster of processor %"PRIu32,
i, cluster_start, cluster_start);
return false;
}
} else {
/*
* The cluster suggest by the heuristic was not parsed from system siblings lists.
* For all processors we expect in the cluster, check that:
* - They have no pre-assigned cluster from siblings lists.
* - If their min/max CPU frequency is known, it is the same.
* - If any part of their MIDR (Implementer, Variant, Part, Revision) is known, it is the same.
*/
if (processors[i].flags & CPUINFO_LINUX_FLAG_PACKAGE_CLUSTER) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"processor %"PRIu32" is expected to be unassigned to any cluster, "
"but system siblings lists reported it to belong to the cluster of processor %"PRIu32,
i, processors[i].package_leader_id);
return false;
}
if (processors[i].flags & CPUINFO_LINUX_FLAG_MIN_FREQUENCY) {
if (cluster_flags & CPUINFO_LINUX_FLAG_MIN_FREQUENCY) {
if (cluster_min_frequency != processors[i].min_frequency) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"minimum frequency of processor %"PRIu32" (%"PRIu32" KHz) is different than of its expected cluster (%"PRIu32" KHz)",
i, processors[i].min_frequency, cluster_min_frequency);
return false;
}
} else {
cluster_min_frequency = processors[i].min_frequency;
cluster_flags |= CPUINFO_LINUX_FLAG_MIN_FREQUENCY;
}
}
if (processors[i].flags & CPUINFO_LINUX_FLAG_MAX_FREQUENCY) {
if (cluster_flags & CPUINFO_LINUX_FLAG_MAX_FREQUENCY) {
if (cluster_max_frequency != processors[i].max_frequency) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"maximum frequency of processor %"PRIu32" (%"PRIu32" KHz) is different than of its expected cluster (%"PRIu32" KHz)",
i, processors[i].max_frequency, cluster_max_frequency);
return false;
}
} else {
cluster_max_frequency = processors[i].max_frequency;
cluster_flags |= CPUINFO_LINUX_FLAG_MAX_FREQUENCY;
}
}
if (processors[i].flags & CPUINFO_ARM_LINUX_VALID_IMPLEMENTER) {
if (cluster_flags & CPUINFO_ARM_LINUX_VALID_IMPLEMENTER) {
if ((cluster_midr & CPUINFO_ARM_MIDR_IMPLEMENTER_MASK) != (processors[i].midr & CPUINFO_ARM_MIDR_IMPLEMENTER_MASK)) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"CPU Implementer of processor %"PRIu32" (0x%02"PRIx32") is different than of its expected cluster (0x%02"PRIx32")",
i, midr_get_implementer(processors[i].midr), midr_get_implementer(cluster_midr));
return false;
}
} else {
cluster_midr = midr_copy_implementer(cluster_midr, processors[i].midr);
cluster_flags |= CPUINFO_ARM_LINUX_VALID_IMPLEMENTER;
}
}
if (processors[i].flags & CPUINFO_ARM_LINUX_VALID_VARIANT) {
if (cluster_flags & CPUINFO_ARM_LINUX_VALID_VARIANT) {
if ((cluster_midr & CPUINFO_ARM_MIDR_VARIANT_MASK) != (processors[i].midr & CPUINFO_ARM_MIDR_VARIANT_MASK)) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"CPU Variant of processor %"PRIu32" (0x%"PRIx32") is different than of its expected cluster (0x%"PRIx32")",
i, midr_get_variant(processors[i].midr), midr_get_variant(cluster_midr));
return false;
}
} else {
cluster_midr = midr_copy_variant(cluster_midr, processors[i].midr);
cluster_flags |= CPUINFO_ARM_LINUX_VALID_VARIANT;
}
}
if (processors[i].flags & CPUINFO_ARM_LINUX_VALID_PART) {
if (cluster_flags & CPUINFO_ARM_LINUX_VALID_PART) {
if ((cluster_midr & CPUINFO_ARM_MIDR_PART_MASK) != (processors[i].midr & CPUINFO_ARM_MIDR_PART_MASK)) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"CPU Part of processor %"PRIu32" (0x%03"PRIx32") is different than of its expected cluster (0x%03"PRIx32")",
i, midr_get_part(processors[i].midr), midr_get_part(cluster_midr));
return false;
}
} else {
cluster_midr = midr_copy_part(cluster_midr, processors[i].midr);
cluster_flags |= CPUINFO_ARM_LINUX_VALID_PART;
}
}
if (processors[i].flags & CPUINFO_ARM_LINUX_VALID_REVISION) {
if (cluster_flags & CPUINFO_ARM_LINUX_VALID_REVISION) {
if ((cluster_midr & CPUINFO_ARM_MIDR_REVISION_MASK) != (processors[i].midr & CPUINFO_ARM_MIDR_REVISION_MASK)) {
cpuinfo_log_debug(
"heuristic detection of core clusters failed: "
"CPU Revision of processor %"PRIu32" (0x%"PRIx32") is different than of its expected cluster (0x%"PRIx32")",
i, midr_get_revision(cluster_midr), midr_get_revision(processors[i].midr));
return false;
}
} else {
cluster_midr = midr_copy_revision(cluster_midr, processors[i].midr);
cluster_flags |= CPUINFO_ARM_LINUX_VALID_REVISION;
}
}
}
}
expected_cluster_processors--;
}
}
/* Verification passed, assign all processors to new clusters */
cluster = 0;
expected_cluster_processors = 0;
for (uint32_t i = 0; i < max_processors; i++) {
if (bitmask_all(processors[i].flags, CPUINFO_LINUX_FLAG_VALID)) {
if (expected_cluster_processors == 0) {
/* Expect this processor to start a new cluster */
cluster_start = i;
expected_cluster_processors = cluster_processors[cluster++];
} else {
/* Expect this processor to belong to the same cluster as processor */
if (!(processors[i].flags & CPUINFO_LINUX_FLAG_PACKAGE_CLUSTER)) {
cpuinfo_log_debug("assigned processor %"PRIu32" to cluster of processor %"PRIu32" based on heuristic",
i, cluster_start);
}
processors[i].package_leader_id = cluster_start;
processors[i].flags |= CPUINFO_LINUX_FLAG_PACKAGE_CLUSTER;
}
expected_cluster_processors--;
}
}
return true;
}