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show isolated cpus in sysfs

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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: Li Zefan <lizefan@huawei.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Acked-by: Chris Metcalf <cmetcalf@ezchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rik van Riel 2015-04-24 15:24:27 -04:00 committed by Greg Kroah-Hartman
parent e26081808e
commit 59f30abe94
1 changed files with 12 additions and 0 deletions
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12
drivers/base/cpu.c
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@ -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