show nohz_full cpus in sysfs (6570a9a1) · Commits · 戴 / test

Currently there is no way to query which CPUs are in nohz_full mode from userspace. Export the CPU list running in nohz_full mode in sysfs, specifically in the file /sys/devices/system/cpu/nohz_full This can be used by system management tools like libvirt, openstack, and others to ensure proper task placement. 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>

drivers/base/cpu.c

+17 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@
		#include <linux/acpi.h>
		#include <linux/of.h>
		#include <linux/cpufeature.h>
		#include <linux/tick.h>

		#include "base.h"

		@@ -276,6 +277,19 @@ static ssize_t print_cpus_isolated(struct device *dev,
		}
		static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);

		#ifdef CONFIG_NO_HZ_FULL
		static ssize_t print_cpus_nohz_full(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(tick_nohz_full_mask));

		return n;
		}
		static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
		#endif

		static void cpu_device_release(struct device *dev)
		{
		/*
		@@ -443,6 +457,9 @@ static struct attribute *cpu_root_attrs[] = {
		&dev_attr_kernel_max.attr,
		&dev_attr_offline.attr,
		&dev_attr_isolated.attr,
		#ifdef CONFIG_NO_HZ_FULL
		&dev_attr_nohz_full.attr,
		#endif
		#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
		&dev_attr_modalias.attr,
		#endif

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