cpupower: Implement CPU physical core querying

This patch is also an issue report. get_cpu_topology will always save
into cpupower_topology a cores size of 0. The code to handle this looks
like it was commented out, and what is commented out is missing a curly
bracket.

https://elixir.bootlin.com/linux/v6.13.5/source/tools/power/cpupower/lib/cpupower.c#L206-L212

Inspiration was taken from psutil to implement this by querying
core_cpu_list. Instead of using a hashmap, I used a sorted array, and
counted the number of valid unique strings. The counting of this takes
place before the qsort for .pkg as the following code says it is
dependent on the order of that sort.

The previous code claimed Intel CPUs are not numbered correctly. I was
not able to reproduce that issue and removed that comment and the code.

This commit was tested with the libcpupower SWIG Python bindings and
performed correctly on 4 different setups. The most notable is the
Framework Intel laptop; a hybrid system of 4 P cores (8 threads) and 8 E
cores (8 threads).

The 4 setups: A 4 core virt-manager VM running Fedora 41 4c/4t (specs not
listed) was tested as a sanity test for VMs. A Lenovo Ryzen 7 Pro 7840HS
8c/16t. A Supermico Intel(R) Xeon(R) Gold 6330 CPU w/ 56c/112t with 2 CPU
sockets. A Framework 12th Gen Intel(R) Core(TM) i5-1240P with hybrid
cores.

CPU(s):                   16
  On-line CPU(s) list:    0-15
Vendor ID:                AuthenticAMD
  Model name:             AMD Ryzen 7 PRO 7840HS w/ Radeon 780M Graphics
    CPU family:           25
    Model:                116
    Thread(s) per core:   2
    Core(s) per socket:   8
    Socket(s):            1
    Stepping:             1

CPU(s):                   112
  On-line CPU(s) list:    0-111
Vendor ID:                GenuineIntel
  BIOS Vendor ID:         Intel(R) Corporation
  Model name:             Intel(R) Xeon(R) Gold 6330 CPU @ 2.00GHz
    BIOS Model name:      Intel(R) Xeon(R) Gold 6330 CPU @ 2.00GHz  CPU @ 2.0GHz
    BIOS CPU family:      179
    CPU family:           6
    Model:                106
    Thread(s) per core:   2
    Core(s) per socket:   28
    Socket(s):            2
    Stepping:             6

CPU(s):                   16
  On-line CPU(s) list:    0-15
Vendor ID:                GenuineIntel
  Model name:             12th Gen Intel(R) Core(TM) i5-1240P
    CPU family:           6
    Model:                154
    Thread(s) per core:   2
    Core(s) per socket:   12
    Socket(s):            1
    Stepping:             3

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: "John B. Wyatt IV" <[email protected]>
Signed-off-by: "John B. Wyatt IV" <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

Author: John B. Wyatt IV

tools/power/cpupower/lib/cpupower.c

@@ -10,6 +10,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "cpupower.h"
 #include "cpupower_intern.h"
@@ -150,15 +151,25 @@ static int __compare(const void *t1, const void *t2)
 		return 0;
 }
 
+static int __compare_core_cpu_list(const void *t1, const void *t2)
+{
+	struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
+	struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
+
+	return strcmp(top1->core_cpu_list, top2->core_cpu_list);
+}
+
 /*
  * Returns amount of cpus, negative on error, cpu_top must be
  * passed to cpu_topology_release to free resources
  *
- * Array is sorted after ->pkg, ->core, then ->cpu
+ * Array is sorted after ->cpu_smt_list ->pkg, ->core
  */
 int get_cpu_topology(struct cpupower_topology *cpu_top)
 {
 	int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);
+	char path[SYSFS_PATH_MAX];
+	char *last_cpu_list;
 
 	cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
 	if (cpu_top->core_info == NULL)
@@ -183,6 +194,34 @@ int get_cpu_topology(struct cpupower_topology *cpu_top)
 			cpu_top->core_info[cpu].core = -1;
 			continue;
 		}
+		if (cpu_top->core_info[cpu].core == -1) {
+			strncpy(cpu_top->core_info[cpu].core_cpu_list, "-1", CPULIST_BUFFER);
+			continue;
+		}
+		snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
+			 cpu, "core_cpus_list");
+		if (cpupower_read_sysfs(
+			path,
+			cpu_top->core_info[cpu].core_cpu_list,
+			CPULIST_BUFFER) < 1) {
+			printf("Warning CPU%u has a 0 size core_cpus_list string", cpu);
+		}
+	}
+
+	/* Count the number of distinct cpu lists to get the physical core
+	 * count.
+	 */
+	qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
+	      __compare_core_cpu_list);
+
+	last_cpu_list = cpu_top->core_info[0].core_cpu_list;
+	cpu_top->cores = 1;
+	for (cpu = 1; cpu < cpus; cpu++) {
+		if (strcmp(cpu_top->core_info[cpu].core_cpu_list, last_cpu_list) != 0 &&
+		    cpu_top->core_info[cpu].pkg != -1) {
+			last_cpu_list = cpu_top->core_info[cpu].core_cpu_list;
+			cpu_top->cores++;
+		}
 	}
 
 	qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
@@ -203,13 +242,6 @@ int get_cpu_topology(struct cpupower_topology *cpu_top)
 	if (!(cpu_top->core_info[0].pkg == -1))
 		cpu_top->pkgs++;
 
-	/* Intel's cores count is not consecutively numbered, there may
-	 * be a core_id of 3, but none of 2. Assume there always is 0
-	 * Get amount of cores by counting duplicates in a package
-	for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {
-		if (cpu_top->core_info[cpu].core == 0)
-	cpu_top->cores++;
-	*/
 	return cpus;
 }
 

tools/power/cpupower/lib/cpupower.h

@@ -2,6 +2,8 @@
 #ifndef __CPUPOWER_CPUPOWER_H__
 #define __CPUPOWER_CPUPOWER_H__
 
+#define CPULIST_BUFFER 5
+
 struct cpupower_topology {
 	/* Amount of CPU cores, packages and threads per core in the system */
 	unsigned int cores;
@@ -16,6 +18,7 @@ struct cpuid_core_info {
 	int pkg;
 	int core;
 	int cpu;
+	char core_cpu_list[CPULIST_BUFFER];
 
 	/* flags */
 	unsigned int is_online:1;