cregit-Linux how code gets into the kernel

Release 4.11 tools/power/cpupower/lib/cpupower.c

/*
 *  (C) 2004-2009  Dominik Brodowski <linux@dominikbrodowski.de>
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>

#include "cpupower.h"
#include "cpupower_intern.h"


unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen) { int fd; ssize_t numread; fd = open(path, O_RDONLY); if (fd == -1) return 0; numread = read(fd, buf, buflen - 1); if (numread < 1) { close(fd); return 0; } buf[numread] = '\0'; close(fd); return (unsigned int) numread; }

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/* * Detect whether a CPU is online * * Returns: * 1 -> if CPU is online * 0 -> if CPU is offline * negative errno values in error case */
int cpupower_is_cpu_online(unsigned int cpu) { char path[SYSFS_PATH_MAX]; int fd; ssize_t numread; unsigned long long value; char linebuf[MAX_LINE_LEN]; char *endp; struct stat statbuf; snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu); if (stat(path, &statbuf) != 0) return 0; /* * kernel without CONFIG_HOTPLUG_CPU * -> cpuX directory exists, but not cpuX/online file */ snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu); if (stat(path, &statbuf) != 0) return 1; fd = open(path, O_RDONLY); if (fd == -1) return -errno; numread = read(fd, linebuf, MAX_LINE_LEN - 1); if (numread < 1) { close(fd); return -EIO; } linebuf[numread] = '\0'; close(fd); value = strtoull(linebuf, &endp, 0); if (value > 1) return -EINVAL; return value; }

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/* returns -1 on failure, 0 on success */
static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result) { char linebuf[MAX_LINE_LEN]; char *endp; char path[SYSFS_PATH_MAX]; snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s", cpu, fname); if (sysfs_read_file(path, linebuf, MAX_LINE_LEN) == 0) return -1; *result = strtol(linebuf, &endp, 0); if (endp == linebuf || errno == ERANGE) return -1; return 0; }

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static int __compare(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; if (top1->pkg < top2->pkg) return -1; else if (top1->pkg > top2->pkg) return 1; else if (top1->core < top2->core) return -1; else if (top1->core > top2->core) return 1; else if (top1->cpu < top2->cpu) return -1; else if (top1->cpu > top2->cpu) return 1; else return 0; }

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Thomas Renninger130100.00%1100.00%
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/* * 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 */
int get_cpu_topology(struct cpupower_topology *cpu_top) { int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF); cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus); if (cpu_top->core_info == NULL) return -ENOMEM; cpu_top->pkgs = cpu_top->cores = 0; for (cpu = 0; cpu < cpus; cpu++) { cpu_top->core_info[cpu].cpu = cpu; cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu); if(sysfs_topology_read_file( cpu, "physical_package_id", &(cpu_top->core_info[cpu].pkg)) < 0) { cpu_top->core_info[cpu].pkg = -1; cpu_top->core_info[cpu].core = -1; continue; } if(sysfs_topology_read_file( cpu, "core_id", &(cpu_top->core_info[cpu].core)) < 0) { cpu_top->core_info[cpu].pkg = -1; cpu_top->core_info[cpu].core = -1; continue; } } 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++; /* 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; }

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

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