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Message-Id: <1556549045-71814-4-git-send-email-kan.liang@linux.intel.com>
Date: Mon, 29 Apr 2019 07:44:04 -0700
From: kan.liang@...ux.intel.com
To: peterz@...radead.org, tglx@...utronix.de, mingo@...hat.com,
linux-kernel@...r.kernel.org
Cc: eranian@...gle.com, tj@...nel.org, ak@...ux.intel.com,
Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH 3/4] perf cgroup: Add cgroup ID as a key of RB tree
From: Kan Liang <kan.liang@...ux.intel.com>
Current RB tree for pinned/flexible groups doesn't take cgroup into
account. All events on a given CPU will be fed to
pinned/flexible_sched_in(), which relies on perf_cgroup_match() to
filter the events for a specific cgroup. The method has high overhead,
especially in frequent context switch with several events and cgroups
involved.
Add unique cgrp_id for each cgroup, which is composed by CPU ID and css
subsys-unique ID. The low 32bit of cgrp_id (css subsys-unique ID) is
used as part of complex key of RB tree.
Events in the same cgroup has the same cgrp_id.
The cgrp_id is always zero for non-cgroup case. There is no functional
change for non-cgroup case.
Add perf_event_groups_first_cgroup() and
perf_event_groups_next_cgroup(), which will be used later to traverse
the events for a specific cgroup on a given CPU.
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
include/linux/perf_event.h | 6 ++++
kernel/events/core.c | 84 ++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 83 insertions(+), 7 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 039e2f2..7eff286 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -703,6 +703,7 @@ struct perf_event {
#ifdef CONFIG_CGROUP_PERF
struct perf_cgroup *cgrp; /* cgroup event is attach to */
+ u64 cgrp_id; /* perf cgroup ID */
#endif
struct list_head sb_list;
@@ -825,6 +826,9 @@ struct bpf_perf_event_data_kern {
#ifdef CONFIG_CGROUP_PERF
+#define PERF_CGROUP_ID_MASK 0xffffffff
+#define cgrp_id_low(id) (id & PERF_CGROUP_ID_MASK)
+
/*
* perf_cgroup_info keeps track of time_enabled for a cgroup.
* This is a per-cpu dynamically allocated data structure.
@@ -837,6 +841,8 @@ struct perf_cgroup_info {
struct perf_cgroup {
struct cgroup_subsys_state css;
struct perf_cgroup_info __percpu *info;
+ /* perf cgroup ID = (CPU ID << 32) | css subsys-unique ID */
+ u64 __percpu *cgrp_id;
};
/*
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 782fd86..5ecc048 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -901,6 +901,7 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event,
struct cgroup_subsys_state *css;
struct fd f = fdget(fd);
int ret = 0;
+ u64 cgrp_id;
if (!f.file)
return -EBADF;
@@ -915,6 +916,10 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event,
cgrp = container_of(css, struct perf_cgroup, css);
event->cgrp = cgrp;
+ cgrp_id = ((u64)smp_processor_id() << 32) | css->id;
+ event->cgrp_id = cgrp_id;
+ *per_cpu_ptr(cgrp->cgrp_id, event->cpu) = cgrp_id;
+
/*
* all events in a group must monitor
* the same cgroup because a task belongs
@@ -1494,6 +1499,9 @@ static void init_event_group(struct perf_event *event)
{
RB_CLEAR_NODE(&event->group_node);
event->group_index = 0;
+#ifdef CONFIG_CGROUP_PERF
+ event->cgrp_id = 0;
+#endif
}
/*
@@ -1521,8 +1529,8 @@ static void perf_event_groups_init(struct perf_event_groups *groups)
/*
* Compare function for event groups;
*
- * Implements complex key that first sorts by CPU and then by virtual index
- * which provides ordering when rotating groups for the same CPU.
+ * Implements complex key that first sorts by CPU and cgroup ID, then by
+ * virtual index which provides ordering when rotating groups for the same CPU.
*/
static bool
perf_event_groups_less(struct perf_event *left, struct perf_event *right)
@@ -1532,6 +1540,13 @@ perf_event_groups_less(struct perf_event *left, struct perf_event *right)
if (left->cpu > right->cpu)
return false;
+#ifdef CONFIG_CGROUP_PERF
+ if (cgrp_id_low(left->cgrp_id) < cgrp_id_low(right->cgrp_id))
+ return true;
+ if (cgrp_id_low(left->cgrp_id) > cgrp_id_low(right->cgrp_id))
+ return false;
+#endif
+
if (left->group_index < right->group_index)
return true;
if (left->group_index > right->group_index)
@@ -1541,7 +1556,8 @@ perf_event_groups_less(struct perf_event *left, struct perf_event *right)
}
/*
- * Insert @event into @groups' tree; using {@...nt->cpu, ++@...ups->index} for
+ * Insert @event into @groups' tree;
+ * Using {@...nt->cpu, @event->cgrp_id, ++@...ups->index} for
* key (see perf_event_groups_less). This places it last inside the CPU
* subtree.
*/
@@ -1650,6 +1666,50 @@ perf_event_groups_next(struct perf_event *event)
return NULL;
}
+#ifdef CONFIG_CGROUP_PERF
+
+static struct perf_event *
+perf_event_groups_first_cgroup(struct perf_event_groups *groups,
+ int cpu, u64 cgrp_id)
+{
+ struct perf_event *node_event = NULL, *match = NULL;
+ struct rb_node *node = groups->tree.rb_node;
+
+ while (node) {
+ node_event = container_of(node, struct perf_event, group_node);
+
+ if (cpu < node_event->cpu) {
+ node = node->rb_left;
+ } else if (cpu > node_event->cpu) {
+ node = node->rb_right;
+ } else {
+ if (cgrp_id_low(cgrp_id) < cgrp_id_low(node_event->cgrp_id))
+ node = node->rb_left;
+ else if (cgrp_id_low(cgrp_id) > cgrp_id_low(node_event->cgrp_id))
+ node = node->rb_right;
+ else {
+ match = node_event;
+ node = node->rb_left;
+ }
+ }
+ }
+ return match;
+}
+
+static struct perf_event *
+perf_event_groups_next_cgroup(struct perf_event *event)
+{
+ struct perf_event *next;
+
+ next = rb_entry_safe(rb_next(&event->group_node), typeof(*event), group_node);
+ if (next && (next->cpu == event->cpu) && (next->cgrp_id == event->cgrp_id))
+ return next;
+
+ return NULL;
+}
+
+#endif
+
/*
* Iterate through the whole groups tree.
*/
@@ -12127,18 +12187,28 @@ perf_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
return ERR_PTR(-ENOMEM);
jc->info = alloc_percpu(struct perf_cgroup_info);
- if (!jc->info) {
- kfree(jc);
- return ERR_PTR(-ENOMEM);
- }
+ if (!jc->info)
+ goto free_jc;
+
+ jc->cgrp_id = alloc_percpu(u64);
+ if (!jc->cgrp_id)
+ goto free_jc_info;
return &jc->css;
+
+free_jc_info:
+ free_percpu(jc->info);
+free_jc:
+ kfree(jc);
+
+ return ERR_PTR(-ENOMEM);
}
static void perf_cgroup_css_free(struct cgroup_subsys_state *css)
{
struct perf_cgroup *jc = container_of(css, struct perf_cgroup, css);
+ free_percpu(jc->cgrp_id);
free_percpu(jc->info);
kfree(jc);
}
--
2.7.4
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