Commit 01bcb56f authored by Srinivas Pandruvada's avatar Srinivas Pandruvada
Browse files

tools/power/x86/intel-speed-select: Prevent CPU 0 offline 



Kernel 6.5 version deprecated CPU 0 hotplug. This will cause all
requests to fail to offline CPU 0. Check version number of kernel
and ignore CPU 0 hotplug request with debug aid to use cgroup
isolation feature for CPU 0.

Signed-off-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
parent e67b6ed2

tools/power/x86/intel-speed-select/isst-config.c

+34 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
 */



#include <linux/isst_if.h>

#include <sys/utsname.h>



#include "isst.h"
@@ -473,11 +474,44 @@ static unsigned int is_cpu_online(int cpu) 
	return online;

}



static int get_kernel_version(int *major, int *minor)

{

	struct utsname buf;

	int ret;



	ret = uname(&buf);

	if (ret)

		return ret;



	ret = sscanf(buf.release, "%d.%d", major, minor);

	if (ret != 2)

		return ret;



	return 0;

}



#define CPU0_HOTPLUG_DEPRECATE_MAJOR_VER	6

#define CPU0_HOTPLUG_DEPRECATE_MINOR_VER	5



void set_cpu_online_offline(int cpu, int state)

{

	char buffer[128];

	int fd, ret;



	if (!cpu) {

		int major, minor;



		ret = get_kernel_version(&major, &minor);

		if (!ret) {

			if (major > CPU0_HOTPLUG_DEPRECATE_MAJOR_VER || (major == CPU0_HOTPLUG_DEPRECATE_MAJOR_VER &&

				minor >= CPU0_HOTPLUG_DEPRECATE_MINOR_VER)) {

				debug_printf("Ignore CPU 0 offline/online for kernel version >= %d.%d\n", major, minor);

				debug_printf("Use cgroups to isolate CPU 0\n");

				return;

			}

		}

	}



	snprintf(buffer, sizeof(buffer),

		 "/sys/devices/system/cpu/cpu%d/online", cpu);