tools/power/cpupower: allow running without cpu0

Linux-3.7 added CONFIG_BOOTPARAM_HOTPLUG_CPU0,
allowing systems to offline cpu0.

But when cpu0 is offline, cpupower monitor will not display all
processor and Mperf information:

[root@intel-skylake-dh-03 cpupower]# ./cpupower monitor
WARNING: at least one cpu is offline
|Idle_Stats
CPU | POLL | C1-S | C1E- | C3-S | C6-S | C7s- | C8-S
4| 0.00| 0.00| 0.00| 0.00| 0.90| 0.00| 96.13
1| 0.00| 0.00| 5.49| 0.00| 0.01| 0.00| 92.26
5| 0.00| 0.00| 0.00| 0.00| 0.46| 0.00| 99.50
2| 45.42| 0.00| 0.00| 0.00| 22.94| 0.00| 28.84
6| 0.00| 37.54| 0.00| 0.00| 0.00| 0.00| 0.00
3| 0.00| 0.00| 0.00| 0.00| 0.30| 0.00| 91.99
7| 0.00| 0.00| 0.00| 0.00| 4.70| 0.00| 0.70

This patch replaces the hard-coded use of cpu0 in cpupower with the
current cpu, allowing it to run without a cpu0.

After the patch is applied,

[root@intel-skylake-dh-03 cpupower]# ./cpupower monitor
WARNING: at least one cpu is offline
|Nehalem || Mperf || Idle_Stats
CPU | C3 | C6 | PC3 | PC6 || C0 | Cx | Freq || POLL | C1-S | C1E- | C3-S | C6-S | C7s- | C8-S
4| 0.01| 1.27| 0.00| 0.00|| 0.04| 99.96| 3957|| 0.00| 0.00| 0.00| 0.00| 1.43| 0.00| 98.52
1| 0.00| 98.82| 0.00| 0.00|| 0.05| 99.95| 3361|| 0.00| 0.00| 0.01| 0.00| 0.03| 0.00| 99.88
5| 0.00| 98.82| 0.00| 0.00|| 0.09| 99.91| 3917|| 0.00| 0.00| 0.00| 0.00| 99.38| 0.00| 0.50
2| 0.33| 0.00| 0.00| 0.00|| 0.00|100.00| 3890|| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00|100.00
6| 0.33| 0.00| 0.00| 0.00|| 0.01| 99.99| 3903|| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 99.99
3| 0.01| 0.71| 0.00| 0.00|| 0.06| 99.94| 3678|| 0.00| 0.00| 0.00| 0.00| 0.80| 0.00| 99.13
7| 0.01| 0.71| 0.00| 0.00|| 0.03| 99.97| 3538|| 0.00| 0.69| 11.70| 0.00| 0.00| 0.00| 87.57

There are some minor cleanups included in this patch.

Signed-off-by: Prarit Bhargava <[e-mail]>
Signed-off-by: Thomas Renninger <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

tools/power/cpupower/utils/cpupower.c

···
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
+#include <sched.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/utsname.h>
···
  */
 struct cpupower_cpu_info cpupower_cpu_info;
 int run_as_root;
+int base_cpu;
 /* Affected cpus chosen by -c/--cpu param */
 struct bitmask *cpus_chosen;
 
···
 	unsigned int i, ret;
 	struct stat statbuf;
 	struct utsname uts;
+	char pathname[32];
 
 	cpus_chosen = bitmask_alloc(sysconf(_SC_NPROCESSORS_CONF));
 
···
 		argv[0] = cmd = "help";
 	}
 
-	get_cpu_info(0, &cpupower_cpu_info);
+	base_cpu = sched_getcpu();
+	if (base_cpu < 0) {
+		fprintf(stderr, _("No valid cpus found.\n"));
+		return EXIT_FAILURE;
+	}
+
+	get_cpu_info(&cpupower_cpu_info);
 	run_as_root = !geteuid();
 	if (run_as_root) {
 		ret = uname(&uts);
+		sprintf(pathname, "/dev/cpu/%d/msr", base_cpu);
 		if (!ret && !strcmp(uts.machine, "x86_64") &&
-		    stat("/dev/cpu/0/msr", &statbuf) != 0) {
+		    stat(pathname, &statbuf) != 0) {
 			if (system("modprobe msr") == -1)
 	fprintf(stderr, _("MSR access not available.\n"));
 		}
 	}
-		
 
 	for (i = 0; i < ARRAY_SIZE(commands); i++) {
 		struct cmd_struct *p = commands + i;

tools/power/cpupower/utils/helpers/cpuid.c

···
  *
  * TBD: Should there be a cpuid alternative for this if /proc is not mounted?
  */
-int get_cpu_info(unsigned int cpu, struct cpupower_cpu_info *cpu_info)
+int get_cpu_info(struct cpupower_cpu_info *cpu_info)
 {
 	FILE *fp;
 	char value[64];
···
 		if (!strncmp(value, "processor\t: ", 12))
 			sscanf(value, "processor\t: %u", &proc);
 
-		if (proc != cpu)
+		if (proc != (unsigned int)base_cpu)
 			continue;
 
 		/* Get CPU vendor */

tools/power/cpupower/utils/helpers/helpers.h

···
 /* Internationalization ****************************/
 
 extern int run_as_root;
+extern int base_cpu;
 extern struct bitmask *cpus_chosen;
 
 /* Global verbose (-d) stuff *********************************/
···
  *
  * Extract CPU vendor, family, model, stepping info from /proc/cpuinfo
  *
- * Returns 0 on success or a negativ error code
+ * Returns 0 on success or a negative error code
  * Only used on x86, below global's struct values are zero/unknown on
  * other archs
  */
-extern int get_cpu_info(unsigned int cpu, struct cpupower_cpu_info *cpu_info);
+extern int get_cpu_info(struct cpupower_cpu_info *cpu_info);
 extern struct cpupower_cpu_info cpupower_cpu_info;
 /* cpuid and cpuinfo helpers  **************************/
 

tools/power/cpupower/utils/helpers/misc.c

···
 
 	*support = *active = *states = 0;
 
-	ret = get_cpu_info(0, &cpu_info);
+	ret = get_cpu_info(&cpu_info);
 	if (ret)
 		return ret;
 

tools/power/cpupower/utils/idle_monitor/hsw_ext_idle.c

···
 			previous_count[num][cpu] = val;
 		}
 	}
-	hsw_ext_get_count(TSC, &tsc_at_measure_start, 0);
+	hsw_ext_get_count(TSC, &tsc_at_measure_start, base_cpu);
 	return 0;
 }
 
···
 	unsigned long long val;
 	int num, cpu;
 
-	hsw_ext_get_count(TSC, &tsc_at_measure_end, 0);
+	hsw_ext_get_count(TSC, &tsc_at_measure_end, base_cpu);
 
 	for (num = 0; num < HSW_EXT_CSTATE_COUNT; num++) {
 		for (cpu = 0; cpu < cpu_count; cpu++) {

tools/power/cpupower/utils/idle_monitor/mperf_monitor.c

···
 static int mperf_get_tsc(unsigned long long *tsc)
 {
 	int ret;
-	ret = read_msr(0, MSR_TSC, tsc);
+
+	ret = read_msr(base_cpu, MSR_TSC, tsc);
 	if (ret)
 		dprint("Reading TSC MSR failed, returning %llu\n", *tsc);
 	return ret;

tools/power/cpupower/utils/idle_monitor/nhm_idle.c

···
 	int num, cpu;
 	unsigned long long dbg, val;
 
-	nhm_get_count(TSC, &tsc_at_measure_start, 0);
+	nhm_get_count(TSC, &tsc_at_measure_start, base_cpu);
 
 	for (num = 0; num < NHM_CSTATE_COUNT; num++) {
 		for (cpu = 0; cpu < cpu_count; cpu++) {
···
 			previous_count[num][cpu] = val;
 		}
 	}
-	nhm_get_count(TSC, &dbg, 0);
+	nhm_get_count(TSC, &dbg, base_cpu);
 	dprint("TSC diff: %llu\n", dbg - tsc_at_measure_start);
 	return 0;
 }
···
 	unsigned long long dbg;
 	int num, cpu;
 
-	nhm_get_count(TSC, &tsc_at_measure_end, 0);
+	nhm_get_count(TSC, &tsc_at_measure_end, base_cpu);
 
 	for (num = 0; num < NHM_CSTATE_COUNT; num++) {
 		for (cpu = 0; cpu < cpu_count; cpu++) {
···
 			current_count[num][cpu] = val;
 		}
 	}
-	nhm_get_count(TSC, &dbg, 0);
+	nhm_get_count(TSC, &dbg, base_cpu);
 	dprint("TSC diff: %llu\n", dbg - tsc_at_measure_end);
 
 	return 0;

tools/power/cpupower/utils/idle_monitor/snb_idle.c

···
 			previous_count[num][cpu] = val;
 		}
 	}
-	snb_get_count(TSC, &tsc_at_measure_start, 0);
+	snb_get_count(TSC, &tsc_at_measure_start, base_cpu);
 	return 0;
 }
 
···
 	unsigned long long val;
 	int num, cpu;
 
-	snb_get_count(TSC, &tsc_at_measure_end, 0);
+	snb_get_count(TSC, &tsc_at_measure_end, base_cpu);
 
 	for (num = 0; num < SNB_CSTATE_COUNT; num++) {
 		for (cpu = 0; cpu < cpu_count; cpu++) {