Commit 4c476d8c authored by Roman Gushchin's avatar Roman Gushchin Committed by Tejun Heo
Browse files

cgroup: add tracing points for cgroup v2 freezer 



Add cgroup:cgroup_freeze and cgroup:cgroup_unfreeze events,
which are using the existing cgroup tracing infrastructure.

Add the cgroup_event event class, which is similar to the cgroup
class, but contains an additional integer field to store a new
value (the level field is dropped).

Also add two tracing events: cgroup_notify_populated and
cgroup_notify_frozen, which are raised in a generic way using
the TRACE_CGROUP_PATH() macro.

This allows to trace cgroup state transitions and is generally
helpful for debugging the cgroup freezer code.

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 712e3517

include/trace/events/cgroup.h

+55 −0
Original line number Diff line number Diff line
@@ -103,6 +103,20 @@ DEFINE_EVENT(cgroup, cgroup_rename, 
	TP_ARGS(cgrp, path)

);



DEFINE_EVENT(cgroup, cgroup_freeze,



	TP_PROTO(struct cgroup *cgrp, const char *path),



	TP_ARGS(cgrp, path)

);



DEFINE_EVENT(cgroup, cgroup_unfreeze,



	TP_PROTO(struct cgroup *cgrp, const char *path),



	TP_ARGS(cgrp, path)

);



DECLARE_EVENT_CLASS(cgroup_migrate,



	TP_PROTO(struct cgroup *dst_cgrp, const char *path,
@@ -149,6 +163,47 @@ DEFINE_EVENT(cgroup_migrate, cgroup_transfer_tasks, 
	TP_ARGS(dst_cgrp, path, task, threadgroup)

);



DECLARE_EVENT_CLASS(cgroup_event,



	TP_PROTO(struct cgroup *cgrp, const char *path, int val),



	TP_ARGS(cgrp, path, val),



	TP_STRUCT__entry(

		__field(	int,		root			)

		__field(	int,		id			)

		__field(	int,		level			)

		__string(	path,		path			)

		__field(	int,		val			)

	),



	TP_fast_assign(

		__entry->root = cgrp->root->hierarchy_id;

		__entry->id = cgrp->id;

		__entry->level = cgrp->level;

		__assign_str(path, path);

		__entry->val = val;

	),



	TP_printk("root=%d id=%d level=%d path=%s val=%d",

		  __entry->root, __entry->id, __entry->level, __get_str(path),

		  __entry->val)

);



DEFINE_EVENT(cgroup_event, cgroup_notify_populated,



	TP_PROTO(struct cgroup *cgrp, const char *path, int val),



	TP_ARGS(cgrp, path, val)

);



DEFINE_EVENT(cgroup_event, cgroup_notify_frozen,



	TP_PROTO(struct cgroup *cgrp, const char *path, int val),



	TP_ARGS(cgrp, path, val)

);



#endif /* _TRACE_CGROUP_H */



/* This part must be outside protection */

kernel/cgroup/cgroup.c

+2 −0
Original line number Diff line number Diff line
@@ -816,6 +816,8 @@ static void cgroup_update_populated(struct cgroup *cgrp, bool populated) 
			break;



		cgroup1_check_for_release(cgrp);

		TRACE_CGROUP_PATH(notify_populated, cgrp,

				  cgroup_is_populated(cgrp));

		cgroup_file_notify(&cgrp->events_file);



		child = cgrp;

kernel/cgroup/freezer.c

+14 −1
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ 


#include "cgroup-internal.h"



#include <trace/events/cgroup.h>



/*

 * Propagate the cgroup frozen state upwards by the cgroup tree.

 */
@@ -28,6 +30,7 @@ static void cgroup_propagate_frozen(struct cgroup *cgrp, bool frozen) 
			    cgrp->nr_descendants) {

				set_bit(CGRP_FROZEN, &cgrp->flags);

				cgroup_file_notify(&cgrp->events_file);

				TRACE_CGROUP_PATH(notify_frozen, cgrp, 1);

				desc++;

			}

		} else {
@@ -35,6 +38,7 @@ static void cgroup_propagate_frozen(struct cgroup *cgrp, bool frozen) 
			if (test_bit(CGRP_FROZEN, &cgrp->flags)) {

				clear_bit(CGRP_FROZEN, &cgrp->flags);

				cgroup_file_notify(&cgrp->events_file);

				TRACE_CGROUP_PATH(notify_frozen, cgrp, 0);

				desc++;

			}

		}
@@ -73,6 +77,7 @@ void cgroup_update_frozen(struct cgroup *cgrp) 
		clear_bit(CGRP_FROZEN, &cgrp->flags);

	}

	cgroup_file_notify(&cgrp->events_file);

	TRACE_CGROUP_PATH(notify_frozen, cgrp, frozen);



	/* Update the state of ancestor cgroups. */

	cgroup_propagate_frozen(cgrp, frozen);
@@ -189,6 +194,11 @@ static void cgroup_do_freeze(struct cgroup *cgrp, bool freeze) 
		clear_bit(CGRP_FREEZE, &cgrp->flags);

	spin_unlock_irq(&css_set_lock);



	if (freeze)

		TRACE_CGROUP_PATH(freeze, cgrp);

	else

		TRACE_CGROUP_PATH(unfreeze, cgrp);



	css_task_iter_start(&cgrp->self, 0, &it);

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

		/*
@@ -312,6 +322,9 @@ void cgroup_freeze(struct cgroup *cgrp, bool freeze) 
	 * In both cases it's better to notify a user, that there is

	 * nothing to wait for.

	 */

	if (!applied)

	if (!applied) {

		TRACE_CGROUP_PATH(notify_frozen, cgrp,

				  test_bit(CGRP_FROZEN, &cgrp->flags));

		cgroup_file_notify(&cgrp->events_file);

	}

}

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