From 4c476d8cff48853645abc822154aaad208faebcc Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Fri, 19 Apr 2019 10:03:08 -0700 Subject: 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 Signed-off-by: Tejun Heo --- kernel/cgroup/cgroup.c | 2 ++ kernel/cgroup/freezer.c | 15 ++++++++++++++- 2 files changed, 16 insertions(+), 1 deletion(-) (limited to 'kernel') 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 + /* * 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); + } } -- cgit v1.2.3-71-gd317