Commit de201559 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

sched/isolation: Introduce housekeeping flags 



Before we implement isolcpus under housekeeping, we need the isolation
features to be more finegrained. For example some people want NOHZ_FULL
without the full scheduler isolation, others want full scheduler
isolation without NOHZ_FULL.

So let's cut all these isolation features piecewise, at the risk of
overcutting it right now. We can still merge some flags later if they
always make sense together.

Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-9-git-send-email-frederic@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5c4991e2

drivers/net/ethernet/tile/tilegx.c

+2 −2
Original line number Diff line number Diff line
@@ -2270,8 +2270,8 @@ static int __init tile_net_init_module(void) 
		tile_net_dev_init(name, mac);



	if (!network_cpus_init())

		cpumask_and(&network_cpus_map, housekeeping_cpumask(),

			    cpu_online_mask);

		cpumask_and(&network_cpus_map,

			    housekeeping_cpumask(HK_FLAG_MISC), cpu_online_mask);



	return 0;

}

include/linux/sched/isolation.h

+17 −9
Original line number Diff line number Diff line
@@ -5,35 +5,43 @@ 
#include <linux/init.h>

#include <linux/tick.h>



enum hk_flags {

	HK_FLAG_TIMER		= 1,

	HK_FLAG_RCU		= (1 << 1),

	HK_FLAG_MISC		= (1 << 2),

	HK_FLAG_SCHED		= (1 << 3),

};



#ifdef CONFIG_CPU_ISOLATION

DECLARE_STATIC_KEY_FALSE(housekeeping_overriden);

extern int housekeeping_any_cpu(void);

extern const struct cpumask *housekeeping_cpumask(void);

extern void housekeeping_affine(struct task_struct *t);

extern bool housekeeping_test_cpu(int cpu);

extern int housekeeping_any_cpu(enum hk_flags flags);

extern const struct cpumask *housekeeping_cpumask(enum hk_flags flags);

extern void housekeeping_affine(struct task_struct *t, enum hk_flags flags);

extern bool housekeeping_test_cpu(int cpu, enum hk_flags flags);

extern void __init housekeeping_init(void);



#else



static inline int housekeeping_any_cpu(void)

static inline int housekeeping_any_cpu(enum hk_flags flags)

{

	return smp_processor_id();

}



static inline const struct cpumask *housekeeping_cpumask(void)

static inline const struct cpumask *housekeeping_cpumask(enum hk_flags flags)

{

	return cpu_possible_mask;

}



static inline void housekeeping_affine(struct task_struct *t) { }

static inline void housekeeping_affine(struct task_struct *t,

				       enum hk_flags flags) { }

static inline void housekeeping_init(void) { }

#endif /* CONFIG_CPU_ISOLATION */



static inline bool housekeeping_cpu(int cpu)

static inline bool housekeeping_cpu(int cpu, enum hk_flags flags)

{

#ifdef CONFIG_CPU_ISOLATION

	if (static_branch_unlikely(&housekeeping_overriden))

		return housekeeping_test_cpu(cpu);

		return housekeeping_test_cpu(cpu, flags);

#endif

	return true;

}

kernel/rcu/tree_plugin.h

+1 −1
Original line number Diff line number Diff line
@@ -2584,7 +2584,7 @@ static void rcu_bind_gp_kthread(void) 


	if (!tick_nohz_full_enabled())

		return;

	housekeeping_affine(current);

	housekeeping_affine(current, HK_FLAG_RCU);

}



/* Record the current task on dyntick-idle entry. */

kernel/rcu/update.c

+1 −1
Original line number Diff line number Diff line
@@ -719,7 +719,7 @@ static int __noreturn rcu_tasks_kthread(void *arg) 
	LIST_HEAD(rcu_tasks_holdouts);



	/* Run on housekeeping CPUs by default.  Sysadm can move if desired. */

	housekeeping_affine(current);

	housekeeping_affine(current, HK_FLAG_RCU);



	/*

	 * Each pass through the following loop makes one check for

kernel/sched/core.c

+4 −4
Original line number Diff line number Diff line
@@ -527,7 +527,7 @@ int get_nohz_timer_target(void) 
	int i, cpu = smp_processor_id();

	struct sched_domain *sd;



	if (!idle_cpu(cpu) && housekeeping_cpu(cpu))

	if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER))

		return cpu;



	rcu_read_lock();
@@ -536,15 +536,15 @@ int get_nohz_timer_target(void) 
			if (cpu == i)

				continue;



			if (!idle_cpu(i) && housekeeping_cpu(i)) {

			if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) {

				cpu = i;

				goto unlock;

			}

		}

	}



	if (!housekeeping_cpu(cpu))

		cpu = housekeeping_any_cpu();

	if (!housekeeping_cpu(cpu, HK_FLAG_TIMER))

		cpu = housekeeping_any_cpu(HK_FLAG_TIMER);

unlock:

	rcu_read_unlock();

	return cpu;

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