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MINOR: cpu-topo: ignore single-core clusters

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Some platforms (several armv7, intel 14900 etc) report one distinct
cluster per core. This is problematic as it cannot let clusters be
used to distinguish real groups of cores, and cannot be used to build
thread groups.

Let's just compare the cluster cpus to the siblings, and ignore it if
they exactly match. We must also take care of not falling back to
core_cpus_list, which can enumerate cores that already have their
cluster assigned (e.g. intel 14900 has 4 4-Ecore clusters in addition
to the 8 Pcores).
This commit is contained in:
Willy Tarreau 2025-01-10 17:25:38 +01:00
parent a4471ea56d
commit 385360fe81
1 changed files with 12 additions and 6 deletions
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18
src/cpu_topo.c
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@ -445,6 +445,7 @@ int cpu_detect_topology(void)
/* detect the presence of some kernel-specific fields */ /* detect the presence of some kernel-specific fields */
no_cache = no_topo = no_capa = no_clust = no_pkg = no_freq = no_cppc = -1; no_cache = no_topo = no_capa = no_clust = no_pkg = no_freq = no_cppc = -1;
for (cpu = 0; cpu <= cpu_topo_lastcpu; cpu++) { for (cpu = 0; cpu <= cpu_topo_lastcpu; cpu++) {
struct hap_cpuset siblings_list = { };
struct hap_cpuset cpus_list; struct hap_cpuset cpus_list;
int next_level = 1; // assume L1 if unknown int next_level = 1; // assume L1 if unknown
int idx, level; int idx, level;
@ -525,18 +526,19 @@ int cpu_detect_topology(void)
* share the same cores, and also to tell apart cores that * share the same cores, and also to tell apart cores that
* support SMT from those which do not. When mixed, generally * support SMT from those which do not. When mixed, generally
* the ones with SMT are big cores and the ones without are the * the ones with SMT are big cores and the ones without are the
* small ones. * small ones. We also read the entry if the cluster_id is not
* known because we'll have to compare both values.
*/ */
if (ha_cpu_topo[cpu].ts_id < 0 && if ((ha_cpu_topo[cpu].ts_id < 0 || ha_cpu_topo[cpu].cl_gid < 0) &&
read_line_to_trash(NUMA_DETECT_SYSTEM_SYSFS_PATH "/cpu/cpu%d/topology/thread_siblings_list", cpu) >= 0) { read_line_to_trash(NUMA_DETECT_SYSTEM_SYSFS_PATH "/cpu/cpu%d/topology/thread_siblings_list", cpu) >= 0) {
parse_cpu_set_args[0] = trash.area; parse_cpu_set_args[0] = trash.area;
parse_cpu_set_args[1] = "\0"; parse_cpu_set_args[1] = "\0";
if (parse_cpu_set(parse_cpu_set_args, &cpus_list, NULL) == 0) { if (parse_cpu_set(parse_cpu_set_args, &siblings_list, NULL) == 0) {
int sib_id = 0; int sib_id = 0;
cpu_id.th_cnt = ha_cpuset_count(&cpus_list); cpu_id.th_cnt = ha_cpuset_count(&siblings_list);
for (cpu2 = 0; cpu2 <= cpu_topo_lastcpu; cpu2++) { for (cpu2 = 0; cpu2 <= cpu_topo_lastcpu; cpu2++) {
if (ha_cpuset_isset(&cpus_list, cpu2)) { if (ha_cpuset_isset(&siblings_list, cpu2)) {
ha_cpu_topo[cpu2].ts_id = cpu_id.ts_id; ha_cpu_topo[cpu2].ts_id = cpu_id.ts_id;
ha_cpu_topo[cpu2].th_cnt = cpu_id.th_cnt; ha_cpu_topo[cpu2].th_cnt = cpu_id.th_cnt;
ha_cpu_topo[cpu2].th_id = sib_id++; ha_cpu_topo[cpu2].th_id = sib_id++;
@ -552,6 +554,9 @@ int cpu_detect_topology(void)
* above as a fallback for package but we don't care here. We * above as a fallback for package but we don't care here. We
* only consider these values if there's more than one CPU per * only consider these values if there's more than one CPU per
* cluster (some kernels such as 6.1 report one cluster per CPU). * cluster (some kernels such as 6.1 report one cluster per CPU).
* Note that we purposely ignore clusters that are reportedly
* equal to the siblings list, because some machines report one
* distinct cluster per *core* (e.g. some armv7 and intel 14900).
*/ */
if (no_clust < 0) { if (no_clust < 0) {
no_clust = !is_file_present(NUMA_DETECT_SYSTEM_SYSFS_PATH "/cpu/cpu%d/topology/cluster_cpus_list", cpu) && no_clust = !is_file_present(NUMA_DETECT_SYSTEM_SYSFS_PATH "/cpu/cpu%d/topology/cluster_cpus_list", cpu) &&
@ -563,7 +568,8 @@ int cpu_detect_topology(void)
read_line_to_trash(NUMA_DETECT_SYSTEM_SYSFS_PATH "/cpu/cpu%d/topology/core_siblings_list", cpu) >= 0)) { read_line_to_trash(NUMA_DETECT_SYSTEM_SYSFS_PATH "/cpu/cpu%d/topology/core_siblings_list", cpu) >= 0)) {
parse_cpu_set_args[0] = trash.area; parse_cpu_set_args[0] = trash.area;
parse_cpu_set_args[1] = "\0"; parse_cpu_set_args[1] = "\0";
if (parse_cpu_set(parse_cpu_set_args, &cpus_list, NULL) == 0 && ha_cpuset_count(&cpus_list) > 1) { if (parse_cpu_set(parse_cpu_set_args, &cpus_list, NULL) == 0 && ha_cpuset_count(&cpus_list) > 1 &&
(memcmp(&cpus_list, &siblings_list, sizeof(cpus_list)) != 0)) {
for (cpu2 = 0; cpu2 <= cpu_topo_lastcpu; cpu2++) { for (cpu2 = 0; cpu2 <= cpu_topo_lastcpu; cpu2++) {
if (ha_cpuset_isset(&cpus_list, cpu2)) { if (ha_cpuset_isset(&cpus_list, cpu2)) {
ha_cpu_topo[cpu2].cl_lid = cpu_id.cl_lid; ha_cpu_topo[cpu2].cl_lid = cpu_id.cl_lid;