tools/power/cpupower/lib/cpupower.c

File Facts

System

Linux kernel

Corpus path

tools/power/cpupower/lib/cpupower.c

Extension

.c

Size

5782 bytes

Lines

252

Domain

Support Tooling And Documentation

Bucket

tools

Inferred role

Support Tooling And Documentation: implementation source

Status

source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

• Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• sys/types.h
• sys/stat.h
• fcntl.h
• unistd.h
• stdio.h
• errno.h
• stdlib.h
• string.h
• cpupower.h
• cpupower_intern.h

Detected Declarations

• function is_valid_path
• function cpupower_read_sysfs
• function cpupower_write_sysfs
• function cpupower_is_cpu_online
• function sysfs_topology_read_file
• function __compare
• function __compare_core_cpu_list
• function get_cpu_topology
• function cpu_topology_release

Annotated Snippet

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),
	      __compare);

	/* Count the number of distinct pkgs values. This works
	   because the primary sort of the core_info struct was just
	   done by pkg value. */
	last_pkg = cpu_top->core_info[0].pkg;
	for(cpu = 1; cpu < cpus; cpu++) {
		if (cpu_top->core_info[cpu].pkg != last_pkg &&
				cpu_top->core_info[cpu].pkg != -1) {

			last_pkg = cpu_top->core_info[cpu].pkg;
			cpu_top->pkgs++;
		}
	}
	if (!(cpu_top->core_info[0].pkg == -1))
		cpu_top->pkgs++;

	return cpus;
}

void cpu_topology_release(struct cpupower_topology cpu_top)
{
	free(cpu_top.core_info);
}

Annotation

• Immediate include surface: `sys/types.h`, `sys/stat.h`, `fcntl.h`, `unistd.h`, `stdio.h`, `errno.h`, `stdlib.h`, `string.h`.
• Detected declarations: `function is_valid_path`, `function cpupower_read_sysfs`, `function cpupower_write_sysfs`, `function cpupower_is_cpu_online`, `function sysfs_topology_read_file`, `function __compare`, `function __compare_core_cpu_list`, `function get_cpu_topology`, `function cpu_topology_release`.
• Atlas domain: Support Tooling And Documentation / tools.
• Implementation status: source implementation candidate.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.