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Commit 7c74d2bc authored by Thomas Renninger's avatar Thomas Renninger Committed by Dominik Brodowski
Browse files

cpupower: Better detect offlined CPUs 



Before, checking for offlined CPUs was done dirty and
it was checked whether topology parsing returned -1 values.
But this is a valid case on a Xen (and possibly other) kernels.

Do proper online/offline checking, also take CONFIG_HOTPLUG_CPU
option into account (no /sys/devices/../cpuX/online file).

Signed-off-by: default avatarThomas Renninger <trenn@suse.de>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 88f984e0

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

+3 −0
Original line number Diff line number Diff line
@@ -96,6 +96,9 @@ struct cpupower_topology { 
		int pkg;

		int core;

		int cpu;



		/* flags */

		unsigned int is_online:1;

	} *core_info;

};

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

+50 −0
Original line number Diff line number Diff line
@@ -56,6 +56,56 @@ static unsigned int sysfs_write_file(const char *path, 
	return (unsigned int) numwrite;

}



/*

 * Detect whether a CPU is online

 *

 * Returns:

 *     1 -> if CPU is online

 *     0 -> if CPU is offline

 *     negative errno values in error case

 */

int sysfs_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 || value < 0)

		return -EINVAL;



	return value;

}



/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */



/*

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

+2 −0
Original line number Diff line number Diff line
@@ -7,6 +7,8 @@ 


extern unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen);



extern int sysfs_is_cpu_online(unsigned int cpu);



extern unsigned long sysfs_get_idlestate_latency(unsigned int cpu,

						unsigned int idlestate);

extern unsigned long sysfs_get_idlestate_usage(unsigned int cpu,

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

+4 −1
Original line number Diff line number Diff line
@@ -41,6 +41,8 @@ struct cpuid_core_info { 
	unsigned int pkg;

	unsigned int thread;

	unsigned int cpu;

	/* flags */

	unsigned int is_online:1;

};



static int __compare(const void *t1, const void *t2)
@@ -78,6 +80,8 @@ int get_cpu_topology(struct cpupower_topology *cpu_top) 
		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 = sysfs_is_cpu_online(cpu);

		cpu_top->core_info[cpu].pkg =

			sysfs_topology_read_file(cpu, "physical_package_id");

		if ((int)cpu_top->core_info[cpu].pkg != -1 &&
@@ -85,7 +89,6 @@ int get_cpu_topology(struct cpupower_topology *cpu_top) 
			cpu_top->pkgs = cpu_top->core_info[cpu].pkg;

		cpu_top->core_info[cpu].core =

			sysfs_topology_read_file(cpu, "core_id");

		cpu_top->core_info[cpu].cpu = cpu;

	}

	cpu_top->pkgs++;

tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c

+7 −3
Original line number Diff line number Diff line
@@ -190,9 +190,13 @@ void print_results(int topology_depth, int cpu) 
			}

		}

	}

	/* cpu offline */

	if (cpu_top.core_info[cpu].pkg == -1 ||

	    cpu_top.core_info[cpu].core == -1) {

	/*

	 * The monitor could still provide useful data, for example

	 * AMD HW counters partly sit in PCI config space.

	 * It's up to the monitor plug-in to check .is_online, this one

	 * is just for additional info.

	 */

	if (!cpu_top.core_info[cpu].is_online) {

		printf(_(" *is offline\n"));

		return;

	} else