9cc5b86568
This is a kernel enhancement that configures the cpu affinity of kernel threads via kernel boot option nohz_full=. When this option is specified, the cpumask is immediately applied upon kthread launch. This does not affect kernel threads that specify cpu and node. This allows CPU isolation (that is not allowing certain threads to execute on certain CPUs) without using the isolcpus=domain parameter, making it possible to enable load balancing on such CPUs during runtime (see kernel-parameters.txt). Note-1: this is based off on Wind River's patch at https://github.com/starlingx-staging/stx-integ/blob/master/kernel/kernel-std/centos/patches/affine-compute-kernel-threads.patch Difference being that this patch is limited to modifying kernel thread cpumask. Behaviour of other threads can be controlled via cgroups or sched_setaffinity. Note-2: Wind River's patch was based off Christoph Lameter's patch at https://lwn.net/Articles/565932/ with the only difference being the kernel parameter changed from kthread to kthread_cpus. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200527142909.23372-3-frederic@kernel.org
61 lines
1.5 KiB
C
61 lines
1.5 KiB
C
#ifndef _LINUX_SCHED_ISOLATION_H
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#define _LINUX_SCHED_ISOLATION_H
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#include <linux/cpumask.h>
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#include <linux/init.h>
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#include <linux/tick.h>
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enum hk_flags {
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HK_FLAG_TIMER = 1,
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HK_FLAG_RCU = (1 << 1),
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HK_FLAG_MISC = (1 << 2),
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HK_FLAG_SCHED = (1 << 3),
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HK_FLAG_TICK = (1 << 4),
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HK_FLAG_DOMAIN = (1 << 5),
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HK_FLAG_WQ = (1 << 6),
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HK_FLAG_MANAGED_IRQ = (1 << 7),
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HK_FLAG_KTHREAD = (1 << 8),
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};
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#ifdef CONFIG_CPU_ISOLATION
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DECLARE_STATIC_KEY_FALSE(housekeeping_overridden);
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extern int housekeeping_any_cpu(enum hk_flags flags);
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extern const struct cpumask *housekeeping_cpumask(enum hk_flags flags);
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extern bool housekeeping_enabled(enum hk_flags flags);
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extern void housekeeping_affine(struct task_struct *t, enum hk_flags flags);
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extern bool housekeeping_test_cpu(int cpu, enum hk_flags flags);
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extern void __init housekeeping_init(void);
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#else
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static inline int housekeeping_any_cpu(enum hk_flags flags)
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{
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return smp_processor_id();
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}
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static inline const struct cpumask *housekeeping_cpumask(enum hk_flags flags)
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{
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return cpu_possible_mask;
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}
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static inline bool housekeeping_enabled(enum hk_flags flags)
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{
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return false;
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}
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static inline void housekeeping_affine(struct task_struct *t,
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enum hk_flags flags) { }
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static inline void housekeeping_init(void) { }
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#endif /* CONFIG_CPU_ISOLATION */
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static inline bool housekeeping_cpu(int cpu, enum hk_flags flags)
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{
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#ifdef CONFIG_CPU_ISOLATION
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if (static_branch_unlikely(&housekeeping_overridden))
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return housekeeping_test_cpu(cpu, flags);
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#endif
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return true;
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}
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#endif /* _LINUX_SCHED_ISOLATION_H */
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