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Date: Sun, 13 Sep 2015 04:12:23 -0700
From: tip-bot for Peter Zijlstra <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: acme@...hat.com, vincent.weaver@...ne.edu, acme@...nel.org,
peterz@...radead.org, hpa@...or.com, linux-kernel@...r.kernel.org,
mpe@...erman.id.au, sukadev@...ux.vnet.ibm.com,
torvalds@...ux-foundation.org, jolsa@...hat.com,
eranian@...gle.com, mingo@...nel.org, tglx@...utronix.de
Subject: [tip:perf/core] perf/core: Invert perf_read_group() loops
Commit-ID: fa8c269353d560b7c28119ad7617029f92e40b15
Gitweb: http://git.kernel.org/tip/fa8c269353d560b7c28119ad7617029f92e40b15
Author: Peter Zijlstra <peterz@...radead.org>
AuthorDate: Thu, 3 Sep 2015 20:07:49 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Sun, 13 Sep 2015 11:27:27 +0200
perf/core: Invert perf_read_group() loops
In order to enable the use of perf_event_read(.group = true), we need
to invert the sibling-child loop nesting of perf_read_group().
Currently we iterate the child list for each sibling, this precludes
using group reads. Flip things around so we iterate each group for
each child.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
[ Made the patch compile and things. ]
Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Link: http://lkml.kernel.org/r/1441336073-22750-7-git-send-email-sukadev@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
kernel/events/core.c | 85 +++++++++++++++++++++++++++++++++-------------------
1 file changed, 55 insertions(+), 30 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4d89866..dd2a0b8 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3862,50 +3862,75 @@ u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
}
EXPORT_SYMBOL_GPL(perf_event_read_value);
-static int perf_read_group(struct perf_event *event,
- u64 read_format, char __user *buf)
+static void __perf_read_group_add(struct perf_event *leader,
+ u64 read_format, u64 *values)
{
- struct perf_event *leader = event->group_leader, *sub;
- struct perf_event_context *ctx = leader->ctx;
- int n = 0, size = 0, ret;
- u64 count, enabled, running;
- u64 values[5];
+ struct perf_event *sub;
+ int n = 1; /* skip @nr */
- lockdep_assert_held(&ctx->mutex);
+ perf_event_read(leader, true);
+
+ /*
+ * Since we co-schedule groups, {enabled,running} times of siblings
+ * will be identical to those of the leader, so we only publish one
+ * set.
+ */
+ if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+ values[n++] += leader->total_time_enabled +
+ atomic64_read(&leader->child_total_time_enabled);
+ }
- count = perf_event_read_value(leader, &enabled, &running);
+ if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+ values[n++] += leader->total_time_running +
+ atomic64_read(&leader->child_total_time_running);
+ }
- values[n++] = 1 + leader->nr_siblings;
- if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
- values[n++] = enabled;
- if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
- values[n++] = running;
- values[n++] = count;
+ /*
+ * Write {count,id} tuples for every sibling.
+ */
+ values[n++] += perf_event_count(leader);
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(leader);
- size = n * sizeof(u64);
+ list_for_each_entry(sub, &leader->sibling_list, group_entry) {
+ values[n++] += perf_event_count(sub);
+ if (read_format & PERF_FORMAT_ID)
+ values[n++] = primary_event_id(sub);
+ }
+}
- if (copy_to_user(buf, values, size))
- return -EFAULT;
+static int perf_read_group(struct perf_event *event,
+ u64 read_format, char __user *buf)
+{
+ struct perf_event *leader = event->group_leader, *child;
+ struct perf_event_context *ctx = leader->ctx;
+ int ret = event->read_size;
+ u64 *values;
- ret = size;
+ lockdep_assert_held(&ctx->mutex);
- list_for_each_entry(sub, &leader->sibling_list, group_entry) {
- n = 0;
+ values = kzalloc(event->read_size, GFP_KERNEL);
+ if (!values)
+ return -ENOMEM;
- values[n++] = perf_event_read_value(sub, &enabled, &running);
- if (read_format & PERF_FORMAT_ID)
- values[n++] = primary_event_id(sub);
+ values[0] = 1 + leader->nr_siblings;
+
+ /*
+ * By locking the child_mutex of the leader we effectively
+ * lock the child list of all siblings.. XXX explain how.
+ */
+ mutex_lock(&leader->child_mutex);
- size = n * sizeof(u64);
+ __perf_read_group_add(leader, read_format, values);
+ list_for_each_entry(child, &leader->child_list, child_list)
+ __perf_read_group_add(child, read_format, values);
- if (copy_to_user(buf + ret, values, size)) {
- return -EFAULT;
- }
+ mutex_unlock(&leader->child_mutex);
- ret += size;
- }
+ if (copy_to_user(buf, values, event->read_size))
+ ret = -EFAULT;
+
+ kfree(values);
return ret;
}
--
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