Commit d41bf8c9 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup, sched: Move basic cpu stats from cgroup.stat to cpu.stat 



The basic cpu stat is currently shown with "cpu." prefix in
cgroup.stat, and the same information is duplicated in cpu.stat when
cpu controller is enabled.  This is ugly and not very scalable as we
want to expand the coverage of stat information which is always
available.

This patch makes cgroup core always create "cpu.stat" file and show
the basic cpu stat there and calls the cpu controller to show the
extra stats when enabled.  This ensures that the same information
isn't presented in multiple places and makes future expansion of basic
stats easier.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent 0d593634

Documentation/cgroup-v2.txt

+5 −10
Original line number Diff line number Diff line
@@ -886,15 +886,6 @@ All cgroup core files are prefixed with "cgroup." 
		A dying cgroup can consume system resources not exceeding

		limits, which were active at the moment of cgroup deletion.



	  cpu.usage_usec

		CPU time consumed in the subtree.



	  cpu.user_usec

		User CPU time consumed in the subtree.



	  cpu.system_usec

		System CPU time consumed in the subtree.





Controllers

===========
@@ -915,12 +906,16 @@ All time durations are in microseconds. 


  cpu.stat

	A read-only flat-keyed file which exists on non-root cgroups.

	This file exists whether the controller is enabled or not.



	It reports the following six stats:

	It always reports the following three stats:



	- usage_usec

	- user_usec

	- system_usec



	and the following three when the controller is enabled:



	- nr_periods

	- nr_throttled

	- throttled_usec

include/linux/cgroup-defs.h

+2 −0
Original line number Diff line number Diff line
@@ -569,6 +569,8 @@ struct cgroup_subsys { 
	void (*css_released)(struct cgroup_subsys_state *css);

	void (*css_free)(struct cgroup_subsys_state *css);

	void (*css_reset)(struct cgroup_subsys_state *css);

	int (*css_extra_stat_show)(struct seq_file *seq,

				   struct cgroup_subsys_state *css);



	int (*can_attach)(struct cgroup_taskset *tset);

	void (*cancel_attach)(struct cgroup_taskset *tset);

include/linux/cgroup.h

+0 −2
Original line number Diff line number Diff line
@@ -703,8 +703,6 @@ static inline void cpuacct_account_field(struct task_struct *tsk, int index, 
					 u64 val) {}

#endif



void cgroup_stat_show_cputime(struct seq_file *seq, const char *prefix);



void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec);

void __cgroup_account_cputime_field(struct cgroup *cgrp,

				    enum cpu_usage_stat index, u64 delta_exec);

kernel/cgroup/cgroup-internal.h

+1 −0
Original line number Diff line number Diff line
@@ -205,6 +205,7 @@ int cgroup_task_count(const struct cgroup *cgrp); 
void cgroup_stat_flush(struct cgroup *cgrp);

int cgroup_stat_init(struct cgroup *cgrp);

void cgroup_stat_exit(struct cgroup *cgrp);

void cgroup_stat_show_cputime(struct seq_file *seq);

void cgroup_stat_boot(void);



/*

kernel/cgroup/cgroup.c

+58 −2
Original line number Diff line number Diff line
@@ -463,6 +463,28 @@ static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, 
		return &cgrp->self;

}



/**

 * cgroup_tryget_css - try to get a cgroup's css for the specified subsystem

 * @cgrp: the cgroup of interest

 * @ss: the subsystem of interest

 *

 * Find and get @cgrp's css assocaited with @ss.  If the css doesn't exist

 * or is offline, %NULL is returned.

 */

static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,

						     struct cgroup_subsys *ss)

{

	struct cgroup_subsys_state *css;



	rcu_read_lock();

	css = cgroup_css(cgrp, ss);

	if (!css || !css_tryget_online(css))

		css = NULL;

	rcu_read_unlock();



	return css;

}



/**

 * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem

 * @cgrp: the cgroup of interest
@@ -3311,9 +3333,38 @@ static int cgroup_stat_show(struct seq_file *seq, void *v) 
	seq_printf(seq, "nr_dying_descendants %d\n",

		   cgroup->nr_dying_descendants);



	cgroup_stat_show_cputime(seq, "cpu.");

	return 0;

}



static int __maybe_unused cgroup_extra_stat_show(struct seq_file *seq,

						 struct cgroup *cgrp, int ssid)

{

	struct cgroup_subsys *ss = cgroup_subsys[ssid];

	struct cgroup_subsys_state *css;

	int ret;



	if (!ss->css_extra_stat_show)

		return 0;



	css = cgroup_tryget_css(cgrp, ss);

	if (!css)

		return 0;



	ret = ss->css_extra_stat_show(seq, css);

	css_put(css);

	return ret;

}



static int cpu_stat_show(struct seq_file *seq, void *v)

{

	struct cgroup *cgrp = seq_css(seq)->cgroup;

	int ret = 0;



	cgroup_stat_show_cputime(seq);

#ifdef CONFIG_CGROUP_SCHED

	ret = cgroup_extra_stat_show(seq, cgrp, cpu_cgrp_id);

#endif

	return ret;

}



static int cgroup_file_open(struct kernfs_open_file *of)
@@ -4423,6 +4474,11 @@ static struct cftype cgroup_base_files[] = { 
		.name = "cgroup.stat",

		.seq_show = cgroup_stat_show,

	},

	{

		.name = "cpu.stat",

		.flags = CFTYPE_NOT_ON_ROOT,

		.seq_show = cpu_stat_show,

	},

	{ }	/* terminate */

};

CRA Git | Maintained and supported by SUSTech CRA and CCSE