libbpf: Add sample_period to creation options

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>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230207081916.3398417-1-arilou@gmail.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 4191a78b2815f69e72fea25110abdeb02a10f5d8..35a698eb825d96c61b8bed28d529ba82adf0c96f 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11673,17 +11673,22 @@ 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 b18581277eb27d6b262b81e234c53265296e0768..2efd80f6f7b924ebcf8c82673144e4e0c4ea02f6 100644 (file)
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1247,8 +1247,10 @@ 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