Commit 94f75314 authored May 15, 2025 by Yury Norov [NVIDIA] Committed by Borislav Petkov (AMD) May 15, 2025

x86/resctrl: Optimize cpumask_any_housekeeping()



With the lack of cpumask_any_andnot_but(), cpumask_any_housekeeping()
has to abuse cpumask_nth() functions.

Update cpumask_any_housekeeping() to use the new cpumask_any_but()
and cpumask_any_andnot_but(). These two functions understand
RESCTRL_PICK_ANY_CPU, which simplifies cpumask_any_housekeeping()
significantly.

Signed-off-by: Yury Norov [NVIDIA] <yury.norov@gmail.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: James Morse <james.morse@arm.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/20250515165855.31452-5-james.morse@arm.com

parent 5da703ef

arch/x86/kernel/cpu/resctrl/internal.h

+7 −21

Original line number	Diff line number	Diff line
		@@ -47,32 +47,18 @@
		static inline unsigned int
		cpumask_any_housekeeping(const struct cpumask *mask, int exclude_cpu)
		{
		unsigned int cpu, hk_cpu;

		if (exclude_cpu == RESCTRL_PICK_ANY_CPU)
		cpu = cpumask_any(mask);
		else
		cpu = cpumask_any_but(mask, exclude_cpu);

		/* Only continue if tick_nohz_full_mask has been initialized. */
		if (!tick_nohz_full_enabled())
		return cpu;

		/* If the CPU picked isn't marked nohz_full nothing more needs doing. */
		if (cpu < nr_cpu_ids && !tick_nohz_full_cpu(cpu))
		return cpu;
		unsigned int cpu;

		/* Try to find a CPU that isn't nohz_full to use in preference */
		hk_cpu = cpumask_nth_andnot(0, mask, tick_nohz_full_mask);
		if (hk_cpu == exclude_cpu)
		hk_cpu = cpumask_nth_andnot(1, mask, tick_nohz_full_mask);

		if (hk_cpu < nr_cpu_ids)
		cpu = hk_cpu;

		if (tick_nohz_full_enabled()) {
		cpu = cpumask_any_andnot_but(mask, tick_nohz_full_mask, exclude_cpu);
		if (cpu < nr_cpu_ids)
		return cpu;
		}

		return cpumask_any_but(mask, exclude_cpu);
		}

		struct rdt_fs_context {
		struct kernfs_fs_context kfc;
		bool enable_cdpl2;