https://bugs.linaro.org/show_bug.cgi?id=3201

--- Comment #1 from Bill Fischofer <bill.fischo...@linaro.org> ---
Thanks, Petri.

The L2fwd numbers are things we should be able to work with. Do you have any
sort of "hot spot" analysis to say where the extra pathlength is coming from in
those runs? The intersect with the DPDK zero-copy stuff is also interesting.

On the microbenchmarks, how repeatable are those numbers? I ask because the
differences even within a single test seems non-intuitive. For example, both
alloc and free tests individually show measurable degradation, but when
combined (alloc_free test) there is either no degradation or measured
improvement. How is that possible?

Similarly, packet_pull_tail is reporting a 77% improvement on 64 byte packets
and a 39% drop on 128 byte packets. Again I don't see how this is possible
since the code is not sensitive to packet size--the code path deltas should be
identical.

Or consider:
bench_packet_l4_offset_set      -39 %   -39 %   83 %    -37 %   -41 %   -37 %

Why should 256-byte packets get a significant boost when other sizes show
degradation?

Or again:
bench_packet_copy_from_mem      -2 %    0 %     -28 %   0 %     -15 %   10 %    

These results are all over the map for no obvious reason.

These anomalies suggest that the microbenchmarks themselves are exhibiting some
randomness which may be obscuring what we're trying to measure / tune.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

Reply via email to