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Commit ef824fa1 authored by Tejun Heo's avatar Tejun Heo
Browse files

perf: make perf_event cgroup hierarchical 



perf_event is one of a couple remaining cgroup controllers with broken
hierarchy support.  Converting it to support hierarchy is almost
trivial.  The only thing necessary is to consider a task belonging to
a descendant cgroup as a match.  IOW, if the cgroup of the currently
executing task (@cpuctx->cgrp) equals or is a descendant of the
event's cgroup (@event->cgrp), then the event should be enabled.

Implement hierarchy support and remove .broken_hierarchy tag along
with the incorrect comment on what needs to be done for hierarchy
support.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Stephane Eranian <eranian@google.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
parent 78574cf9

kernel/events/core.c

+16 −8
Original line number Diff line number Diff line
@@ -251,7 +251,22 @@ perf_cgroup_match(struct perf_event *event) 
	struct perf_event_context *ctx = event->ctx;

	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);



	return !event->cgrp || event->cgrp == cpuctx->cgrp;

	/* @event doesn't care about cgroup */

	if (!event->cgrp)

		return true;



	/* wants specific cgroup scope but @cpuctx isn't associated with any */

	if (!cpuctx->cgrp)

		return false;



	/*

	 * Cgroup scoping is recursive.  An event enabled for a cgroup is

	 * also enabled for all its descendant cgroups.  If @cpuctx's

	 * cgroup is a descendant of @event's (the test covers identity

	 * case), it's a match.

	 */

	return cgroup_is_descendant(cpuctx->cgrp->css.cgroup,

				    event->cgrp->css.cgroup);

}



static inline bool perf_tryget_cgroup(struct perf_event *event)
@@ -7509,12 +7524,5 @@ struct cgroup_subsys perf_subsys = { 
	.css_free	= perf_cgroup_css_free,

	.exit		= perf_cgroup_exit,

	.attach		= perf_cgroup_attach,



	/*

	 * perf_event cgroup doesn't handle nesting correctly.

	 * ctx->nr_cgroups adjustments should be propagated through the

	 * cgroup hierarchy.  Fix it and remove the following.

	 */

	.broken_hierarchy = true,

};

#endif /* CONFIG_CGROUP_PERF */