On Mon, Feb 6, 2023 at 10:08 AM Robin Jarry <rja...@redhat.com> wrote: > > David Marchand, Feb 06, 2023 at 09:58: > > I have been playing a bit with this series with two lcores, each one > > polling a net/null port. > > At first it looked good, but then I started to have one idle lcore, by > > asking net/null not to receive anything. > > > > $ build-clang/app/dpdk-testpmd -c 7 --no-huge -m 40 -a 0:0.0 --vdev > > net_null1,no-rx=1 --vdev net_null2 -- --no-mlockall > > --total-num-mbufs=2048 -ia --record-core-cycles --nb-cores=2 > > > > One thing that struck me is that an idle lcore was always showing less > > "total_cycles" than a busy one. > > The more time testpmd was running, the bigger the divergence between > > lcores would be. > > > > Re-reading the API, it is unclear to me (which is the reason for my > > comments on patch 2). > > Let's first sort out my patch 2 comments and we may revisit this patch > > 4 implementation afterwards (as I think we are not accounting some > > mainloop cycles with current implementation). > > Indeed, we are not accounting for all cycles. Only the cycles spent in > the packet_fwd_t functions. This was already the case before my series > I only added the busy cycles accounting.
"busy" cycles is what was already present in testpmd under the core_cycles report existing feature: get_end_cycles was only called with nb_rx + nb_tx > 0. The only change with this patch is its internal name, there is no addition on this topic. But this patch adds "total_cycles" for testpmd... > > > However, I agree that this should be updated to take all cycles into > account (as much as it is possible with the current code base). Maybe > this could be done as a separate patch or do you want to include it in > this series? ... and its implementation seems non compliant with the lcore_usage API as discussed in patch 2. As for how much cycles are counted as busy (meaning, should we count cycles spent in the mainloop too), I think it is better but that would be a change in the core_cycles report existing feature. I'd really like to hear from testpmd maintainers. -- David Marchand
