int kernctl_put_subbuf(int fd);
int kernctl_buffer_flush(int fd);
+int kernctl_buffer_flush_empty(int fd);
int kernctl_get_metadata_version(int fd, uint64_t *version);
+int kernctl_metadata_cache_dump(int fd);
/* index */
int kernctl_get_timestamp_begin(int fd, uint64_t *timestamp_begin);