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Date: Mon, 12 Apr 2021 21:41:33 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
LKML <linux-kernel@...r.kernel.org>,
Stephane Eranian <eranian@...gle.com>,
Andi Kleen <ak@...ux.intel.com>,
Ian Rogers <irogers@...gle.com>,
Song Liu <songliubraving@...com>
Subject: [PATCH v2 2/2] perf/core: Support reading group events with shared cgroups
This enables reading event group's counter values together with a
PERF_EVENT_IOC_READ_CGROUP command like we do in the regular read().
Users should give a correct size of buffer to be read which includes
the total buffer size and the cgroup id.
Acked-by: Song Liu <songliubraving@...com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
kernel/events/core.c | 120 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 117 insertions(+), 3 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0c6b3848a61f..d483b4b42fe2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2232,13 +2232,24 @@ static void perf_add_cgrp_node_list(struct perf_event *event,
{
struct list_head *cgrp_ctx_list = this_cpu_ptr(&cgroup_ctx_list);
struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx);
+ struct perf_event *sibling;
bool is_first;
lockdep_assert_irqs_disabled();
lockdep_assert_held(&ctx->lock);
+ /* only group leader can be added directly */
+ if (event->group_leader != event)
+ return;
+
+ if (!event_has_cgroup_node(event))
+ return;
+
is_first = list_empty(&ctx->cgrp_node_list);
+
list_add_tail(&event->cgrp_node_entry, &ctx->cgrp_node_list);
+ for_each_sibling_event(sibling, event)
+ list_add_tail(&sibling->cgrp_node_entry, &ctx->cgrp_node_list);
if (is_first)
list_add_tail(&ctx->cgrp_ctx_entry, cgrp_ctx_list);
@@ -2250,15 +2261,25 @@ static void perf_del_cgrp_node_list(struct perf_event *event,
struct perf_event_context *ctx)
{
struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx);
+ struct perf_event *sibling;
lockdep_assert_irqs_disabled();
lockdep_assert_held(&ctx->lock);
+ /* only group leader can be deleted directly */
+ if (event->group_leader != event)
+ return;
+
+ if (!event_has_cgroup_node(event))
+ return;
+
update_cgroup_node(event, cgrp->css.cgroup);
/* to refresh delta when it's enabled */
event->cgrp_node_count = 0;
list_del(&event->cgrp_node_entry);
+ for_each_sibling_event(sibling, event)
+ list_del(&sibling->cgrp_node_entry);
if (list_empty(&ctx->cgrp_node_list))
list_del(&ctx->cgrp_ctx_entry);
@@ -2333,7 +2354,7 @@ static int perf_event_attach_cgroup_node(struct perf_event *event, u64 nr_cgrps,
raw_spin_unlock_irqrestore(&ctx->lock, flags);
- if (is_first && enabled)
+ if (is_first && enabled && event->group_leader == event)
event_function_call(event, perf_attach_cgroup_node, NULL);
return 0;
@@ -2370,8 +2391,8 @@ static void __perf_read_cgroup_node(struct perf_event *event)
}
}
-static int perf_event_read_cgroup_node(struct perf_event *event, u64 read_size,
- u64 cgrp_id, char __user *buf)
+static int perf_event_read_cgrp_node_one(struct perf_event *event, u64 cgrp_id,
+ char __user *buf)
{
struct perf_cgroup_node *cgrp;
struct perf_event_context *ctx = event->ctx;
@@ -2406,6 +2427,92 @@ static int perf_event_read_cgroup_node(struct perf_event *event, u64 read_size,
return n * sizeof(u64);
}
+
+static int perf_event_read_cgrp_node_sibling(struct perf_event *event,
+ u64 read_format, u64 cgrp_id,
+ u64 *values)
+{
+ struct perf_cgroup_node *cgrp;
+ int n = 0;
+
+ cgrp = find_cgroup_node(event, cgrp_id);
+ if (cgrp == NULL)
+ return (read_format & PERF_FORMAT_ID) ? 2 : 1;
+
+ values[n++] = cgrp->count;
+ if (read_format & PERF_FORMAT_ID)
+ values[n++] = primary_event_id(event);
+ return n;
+}
+
+static int perf_event_read_cgrp_node_group(struct perf_event *event, u64 cgrp_id,
+ char __user *buf)
+{
+ struct perf_cgroup_node *cgrp;
+ struct perf_event_context *ctx = event->ctx;
+ struct perf_event *sibling;
+ u64 read_format = event->attr.read_format;
+ unsigned long flags;
+ u64 *values;
+ int n = 1;
+ int ret;
+
+ values = kzalloc(event->read_size, GFP_KERNEL);
+ if (!values)
+ return -ENOMEM;
+
+ values[0] = 1 + event->nr_siblings;
+
+ /* update event count and times (possibly run on other cpu) */
+ (void)perf_event_read(event, true);
+
+ raw_spin_lock_irqsave(&ctx->lock, flags);
+
+ cgrp = find_cgroup_node(event, cgrp_id);
+ if (cgrp == NULL) {
+ raw_spin_unlock_irqrestore(&ctx->lock, flags);
+ kfree(values);
+ return -ENOENT;
+ }
+
+ if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+ values[n++] = cgrp->time_enabled;
+ if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+ values[n++] = cgrp->time_running;
+
+ values[n++] = cgrp->count;
+ if (read_format & PERF_FORMAT_ID)
+ values[n++] = primary_event_id(event);
+
+ for_each_sibling_event(sibling, event) {
+ n += perf_event_read_cgrp_node_sibling(sibling, read_format,
+ cgrp_id, &values[n]);
+ }
+
+ raw_spin_unlock_irqrestore(&ctx->lock, flags);
+
+ ret = copy_to_user(buf, values, n * sizeof(u64));
+ kfree(values);
+ if (ret)
+ return -EFAULT;
+
+ return n * sizeof(u64);
+}
+
+static int perf_event_read_cgroup_node(struct perf_event *event, u64 read_size,
+ u64 cgrp_id, char __user *buf)
+{
+ u64 read_format = event->attr.read_format;
+
+ /* buf = bufsize + cgroup_id + read_buffer */
+ if (read_size < 2 * sizeof(u64) + event->read_size)
+ return -EINVAL;
+
+ if (read_format & PERF_FORMAT_GROUP)
+ return perf_event_read_cgrp_node_group(event, cgrp_id, buf);
+
+ return perf_event_read_cgrp_node_one(event, cgrp_id, buf);
+}
#else /* !CONFIG_CGROUP_PERF */
static inline bool event_can_attach_cgroup(struct perf_event *event)
{
@@ -2511,6 +2618,7 @@ static void perf_group_detach(struct perf_event *event)
if (sibling->state == PERF_EVENT_STATE_ACTIVE)
list_add_tail(&sibling->active_list, get_event_list(sibling));
}
+ perf_add_cgrp_node_list(sibling, event->ctx);
WARN_ON_ONCE(sibling->ctx != event->ctx);
}
@@ -2654,6 +2762,9 @@ __perf_remove_from_context(struct perf_event *event,
perf_group_detach(event);
list_del_event(event, ctx);
+ if (event->state > PERF_EVENT_STATE_OFF)
+ perf_del_cgrp_node_list(event, ctx);
+
if (!ctx->nr_events && ctx->is_active) {
ctx->is_active = 0;
ctx->rotate_necessary = 0;
@@ -3112,6 +3223,9 @@ static int __perf_install_in_context(void *info)
reprogram = cgroup_is_descendant(cgrp->css.cgroup,
event->cgrp->css.cgroup);
}
+
+ if (event->state > PERF_EVENT_STATE_OFF)
+ perf_add_cgrp_node_list(event, ctx);
#endif
if (reprogram) {
--
2.31.1.295.g9ea45b61b8-goog
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