On Wed, Jul 13, 2016 at 12:36:17AM +0200, Daniel Borkmann wrote: > This patch adds support for non-linear data on raw records. It means > that for such data, the newly introduced __output_custom() helper will > be used instead of __output_copy(). __output_custom() will invoke > whatever custom callback is passed in via struct perf_raw_record_frag > to extract the data into the ring buffer slot. > > To keep changes in perf_prepare_sample() and in perf_output_sample() > minimal, size/size_head split was added to perf_raw_record that call > sites fill out, so that two extra tests in fast-path can be avoided. > > The few users of raw records are adapted to initialize their size_head > and frag data; no change in behavior for them. Later patch will extend > BPF side with a first user and callback for this facility, future users > could be things like XDP BPF programs (that work on different context > though and would thus have a different callback), etc.
Why? What problem are we solving?
