linux-kernel - [PATCH v2] bpf: Allocate bpf_event

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Date: Tue, 28 May 2024 23:53:11 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>
Cc: Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...gle.com>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	bpf@...r.kernel.org,
	Aleksei Shchekotikhin <alekseis@...gle.com>,
	Nilay Vaish <nilayvaish@...gle.com>
Subject: [PATCH v2] bpf: Allocate bpf_event_entry with node info

It was reported that accessing perf_event map entry caused pretty high
LLC misses in get_map_perf_counter().  As reading perf_event is allowed
for the local CPU only, I think we can use the target CPU of the event
as hint for the allocation like in perf_event_alloc() so that the event
and the entry can be in the same node at least.

Reported-by: Aleksei Shchekotikhin <alekseis@...gle.com>
Reported-by: Nilay Vaish <nilayvaish@...gle.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
v2) fix build errors

 kernel/bpf/arraymap.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index feabc0193852..067f7cf27042 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -1194,10 +1194,17 @@ static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
 						   struct file *map_file)
 {
 	struct bpf_event_entry *ee;
+	struct perf_event *event = perf_file->private_data;
+	int node = -1;
 
-	ee = kzalloc(sizeof(*ee), GFP_KERNEL);
+#ifdef CONFIG_PERF_EVENTS
+	if (event->cpu >= 0)
+		node = cpu_to_node(event->cpu);
+#endif
+
+	ee = kzalloc_node(sizeof(*ee), GFP_KERNEL, node);
 	if (ee) {
-		ee->event = perf_file->private_data;
+		ee->event = event;
 		ee->perf_file = perf_file;
 		ee->map_file = map_file;
 	}
-- 
2.45.1.288.g0e0cd299f1-goog