[PATCH bpf-next v4] libbpf: Add sample_period to creation options

[Jon Doron <arilou@gmail.com>]

From: Jon Doron <jond@wiz.io>

Add option to set when the perf buffer should wake up, by default the
perf buffer becomes signaled for every event that is being pushed to it.

In case of a high throughput of events it will be more efficient to wake
up only once you have X events ready to be read.

So your application can wakeup once and drain the entire perf buffer.

Signed-off-by: Jon Doron <jond@wiz.io>
---
 tools/lib/bpf/libbpf.c | 9 +++++++--
 tools/lib/bpf/libbpf.h | 4 +++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index eed5cec6f510..cd0bce5482b2 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11710,17 +11710,22 @@ struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
 	const size_t attr_sz = sizeof(struct perf_event_attr);
 	struct perf_buffer_params p = {};
 	struct perf_event_attr attr;
+	__u32 sample_period;
 
 	if (!OPTS_VALID(opts, perf_buffer_opts))
 		return libbpf_err_ptr(-EINVAL);
 
+	sample_period = OPTS_GET(opts, sample_period, 1);
+	if (!sample_period)
+		sample_period = 1;
+
 	memset(&attr, 0, attr_sz);
 	attr.size = attr_sz;
 	attr.config = PERF_COUNT_SW_BPF_OUTPUT;
 	attr.type = PERF_TYPE_SOFTWARE;
 	attr.sample_type = PERF_SAMPLE_RAW;
-	attr.sample_period = 1;
-	attr.wakeup_events = 1;
+	attr.sample_period = sample_period;
+	attr.wakeup_events = sample_period;
 
 	p.attr = &attr;
 	p.sample_cb = sample_cb;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 8777ff21ea1d..8104bd128e6b 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1246,8 +1246,10 @@ typedef void (*perf_buffer_lost_fn)(void *ctx, int cpu, __u64 cnt);
 /* common use perf buffer options */
 struct perf_buffer_opts {
 	size_t sz;
+	__u32 sample_period;
+	size_t :0;
 };
-#define perf_buffer_opts__last_field sz
+#define perf_buffer_opts__last_field sample_period
 
 /**
  * @brief **perf_buffer__new()** creates BPF perfbuf manager for a specified
-- 
2.39.1