[PATCH bpf-next v2] libbpf: Add wakeup_events 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 | 4 ++--
 tools/lib/bpf/libbpf.h | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index eed5cec6f510..6b30ff13922b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11719,8 +11719,8 @@ struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
 	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 = OPTS_GET(opts, wakeup_events, 1);
+	attr.wakeup_events = OPTS_GET(opts, wakeup_events, 1);
 
 	p.attr = &attr;
 	p.sample_cb = sample_cb;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 8777ff21ea1d..e83c0a915dc7 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1246,8 +1246,9 @@ 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 wakeup_events;
 };
-#define perf_buffer_opts__last_field sz
+#define perf_buffer_opts__last_field wakeup_events
 
 /**
  * @brief **perf_buffer__new()** creates BPF perfbuf manager for a specified
-- 
2.39.1