Commit f9a25f77 authored by Mathieu Poirier's avatar Mathieu Poirier Committed by Ingo Molnar
Browse files

cpusets: Rebuild root domain deadline accounting information 



When the topology of root domains is modified by CPUset or CPUhotplug
operations information about the current deadline bandwidth held in the
root domain is lost.

This patch addresses the issue by recalculating the lost deadline
bandwidth information by circling through the deadline tasks held in
CPUsets and adding their current load to the root domain they are
associated with.

Tested-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: default avatarJuri Lelli <juri.lelli@redhat.com>
[ Various additional modifications. ]
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-4-juri.lelli@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4b211f2b

include/linux/cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -150,6 +150,7 @@ struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset, 
struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,

					struct cgroup_subsys_state **dst_cssp);



void cgroup_enable_task_cg_lists(void);

void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,

			 struct css_task_iter *it);

struct task_struct *css_task_iter_next(struct css_task_iter *it);

include/linux/sched.h

+5 −0
Original line number Diff line number Diff line
@@ -295,6 +295,11 @@ enum uclamp_id { 
	UCLAMP_CNT

};



#ifdef CONFIG_SMP

extern struct root_domain def_root_domain;

extern struct mutex sched_domains_mutex;

#endif



struct sched_info {

#ifdef CONFIG_SCHED_INFO

	/* Cumulative counters: */

include/linux/sched/deadline.h

+8 −0
Original line number Diff line number Diff line
@@ -24,3 +24,11 @@ static inline bool dl_time_before(u64 a, u64 b) 
{

	return (s64)(a - b) < 0;

}



#ifdef CONFIG_SMP



struct root_domain;

extern void dl_add_task_root_domain(struct task_struct *p);

extern void dl_clear_root_domain(struct root_domain *rd);



#endif /* CONFIG_SMP */

kernel/cgroup/cgroup.c

+1 −1
Original line number Diff line number Diff line
@@ -1891,7 +1891,7 @@ static int cgroup_reconfigure(struct fs_context *fc) 
 */

static bool use_task_css_set_links __read_mostly;



static void cgroup_enable_task_cg_lists(void)

void cgroup_enable_task_cg_lists(void)

{

	struct task_struct *p, *g;

kernel/cgroup/cpuset.c

+63 −1
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ 
#include <linux/proc_fs.h>

#include <linux/rcupdate.h>

#include <linux/sched.h>

#include <linux/sched/deadline.h>

#include <linux/sched/mm.h>

#include <linux/sched/task.h>

#include <linux/seq_file.h>
@@ -894,6 +895,67 @@ done: 
	return ndoms;

}



static void update_tasks_root_domain(struct cpuset *cs)

{

	struct css_task_iter it;

	struct task_struct *task;



	css_task_iter_start(&cs->css, 0, &it);



	while ((task = css_task_iter_next(&it)))

		dl_add_task_root_domain(task);



	css_task_iter_end(&it);

}



static void rebuild_root_domains(void)

{

	struct cpuset *cs = NULL;

	struct cgroup_subsys_state *pos_css;



	lockdep_assert_held(&cpuset_mutex);

	lockdep_assert_cpus_held();

	lockdep_assert_held(&sched_domains_mutex);



	cgroup_enable_task_cg_lists();



	rcu_read_lock();



	/*

	 * Clear default root domain DL accounting, it will be computed again

	 * if a task belongs to it.

	 */

	dl_clear_root_domain(&def_root_domain);



	cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {



		if (cpumask_empty(cs->effective_cpus)) {

			pos_css = css_rightmost_descendant(pos_css);

			continue;

		}



		css_get(&cs->css);



		rcu_read_unlock();



		update_tasks_root_domain(cs);



		rcu_read_lock();

		css_put(&cs->css);

	}

	rcu_read_unlock();

}



static void

partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],

				    struct sched_domain_attr *dattr_new)

{

	mutex_lock(&sched_domains_mutex);

	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);

	rebuild_root_domains();

	mutex_unlock(&sched_domains_mutex);

}



/*

 * Rebuild scheduler domains.

 *
@@ -931,7 +993,7 @@ static void rebuild_sched_domains_locked(void) 
	ndoms = generate_sched_domains(&doms, &attr);



	/* Have scheduler rebuild the domains */

	partition_sched_domains(ndoms, doms, attr);

	partition_and_rebuild_sched_domains(ndoms, doms, attr);

out:

	put_online_cpus();

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE