On Tue, Nov 21, 2017 at 8:20 AM, Neal Cardwell <ncardw...@google.com> wrote: > On Tue, Nov 21, 2017 at 10:51 AM, Yuchung Cheng <ych...@google.com> wrote: >> On Tue, Nov 21, 2017 at 7:01 AM, Neal Cardwell <ncardw...@google.com> wrote: >>> >>> The original motivation for only allowing TLP in the CA_Open state was >>> to be conservative and avoid having the TLP impose extra load on the >>> bottleneck when it may be congested. Plus if there are any SACKed >>> packets in the SACK scoreboard then there are other existing >>> mechanisms to do speedy loss recovery. >> Neal I like your idea of covering more states in TLP. but shouldn't we >> also fix the tso_deferral_logic to work better w/ PRR in CWR state, b/c >> it's a general transmission issue. > > Yes, I agree it's also worthwhile to see if we can make PRR and TSO > deferral play well together. Sorry, I should have been more clear > about that.
Yes, but tso auto defer is an heuristic, and since we do not have a timer to 'send the partial packet' after we understand the ACK that we were waiting for does not arrive in time, we know that the heuristic is not perfect. Adding a timer (and its overhead) for maybe a fraction of cases might be overkill. 'Fixing' TSO autodefer has been on our plates for ever, we played some games that proved to be too expensive. Although I have not played re-using the new hr timer we added for TCP pacing.
