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Commit 59f30abe authored by Rik van Riel's avatar Rik van Riel Committed by Greg Kroah-Hartman
Browse files

show isolated cpus in sysfs 



After system bootup, there is no totally reliable way to see
which CPUs are isolated, because the kernel may modify the
CPUs specified on the isolcpus= kernel command line option.

Export the CPU list that actually got isolated in sysfs,
specifically in the file /sys/devices/system/cpu/isolated

This can be used by system management tools like libvirt,
openstack, and others to ensure proper placement of tasks.

Suggested-by: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarMike Galbraith <umgwanakikbuti@gmail.com>
Acked-by: default avatarChris Metcalf <cmetcalf@ezchip.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e2608180

drivers/base/cpu.c

+12 −0
Original line number Diff line number Diff line
@@ -265,6 +265,17 @@ static ssize_t print_cpus_offline(struct device *dev, 
}

static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);



static ssize_t print_cpus_isolated(struct device *dev,

				  struct device_attribute *attr, char *buf)

{

	int n = 0, len = PAGE_SIZE-2;



	n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(cpu_isolated_map));



	return n;

}

static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);



static void cpu_device_release(struct device *dev)

{

	/*
@@ -431,6 +442,7 @@ static struct attribute *cpu_root_attrs[] = { 
	&cpu_attrs[2].attr.attr,

	&dev_attr_kernel_max.attr,

	&dev_attr_offline.attr,

	&dev_attr_isolated.attr,

#ifdef CONFIG_GENERIC_CPU_AUTOPROBE

	&dev_attr_modalias.attr,

#endif