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authorRoman Gushchin <guro@fb.com>2019-04-19 10:03:08 -0700
committerTejun Heo <tj@kernel.org>2019-04-19 11:26:49 -0700
commit4c476d8cff48853645abc822154aaad208faebcc (patch)
tree6f548d87c31e12ea213db7af9236e0944ae4f7a4 /kernel/cgroup
parent712e35178754bbb785d00d5fcf5abaf32699bf11 (diff)
downloadlinux-4c476d8cff48853645abc822154aaad208faebcc.tar.bz2
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: Roman Gushchin <guro@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup')
-rw-r--r--kernel/cgroup/cgroup.c2
-rw-r--r--kernel/cgroup/freezer.c15
2 files changed, 16 insertions, 1 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 6895464b54c6..57edcf398d71 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -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;
diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c
index 9d8cda478fc9..3bfbb3c8baf3 100644
--- a/kernel/cgroup/freezer.c
+++ b/kernel/cgroup/freezer.c
@@ -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);
+ }
}