On Wed, Aug 9, 2017 at 8:32 PM, Jerry Chu <hk...@google.com> wrote: > On Wed, Aug 9, 2017 at 5:47 PM, Rao Shoaib <rao.sho...@oracle.com> wrote: >> >> >> On 08/09/2017 05:30 PM, David Miller wrote: >>> >>> From: Joe Smith <codesoldi...@gmail.com> >>> Date: Wed, 9 Aug 2017 17:20:32 -0700 >>> >>>> Making Linux conform to standards and behavior that is logical seems >>>> like a good enough reason. >>> >>> That's an awesome attitude to have when we're implementing something >>> new and don't have the facility already. >>> >>> But when we have something already the only important consideration is >>> not breaking existing apps which rely on that behavior. >>> >>> That is much, much, more important than standards compliance. >>> >>> If users are confused, just fix the documentation. >> >> David, >> >> If it was just confusion than sure fixing the documentation is fine. What if >> the logic is incorrect, does not conform to the standard that is says it is > > Not sure what part of logic is "incorrect" when it was a homegrown Linux API > with no need to conform with any "standard"? Note that the new API was > invented > 7 years ago not out of need for RFC5482. In fact I initially call the option > TCP_FAILFAST and did not even know the existence of RFC5482 until someone > around the same time proposed a UTO option specifically for RFC5482 and I > thought the two can be combined. (This is roughly the memory I can > recollect so far.) > > So you see my focus back then was to devise a "failfast" option whereas > RFC5482 > was meant for a "failslow" case. I think that explains why I let the > option override > keepalive so a TCP connection can "fail fast" while RFC5482 4.2 tries to > prevent > keepalive failure ahead of UTO, favoring "fail slow". > > If we start from a clean slate then perhaps one can argue the semantic > either way > but we do not have a clean slate. For that I still slightly favor not > changing the code > because the risk of breakage is definitely non-zero and the issue you're > having > seem to be only related to documentation.
One more thing - the proposed patch compares TCP_KEEPIDLE against TCP_USER_TIMEOUT. But I don't think TCP_KEEPIDLE is what the "keep-alive timer" referred to in RFC5482. Linux keepalive implementation seems to use # of retries (TCP_KEEPCNT) rather than time duration (keep-alive time) to determine when to quit. If that is the case then your proposed change is not fully "compliant" either and the best is probably just don't change. > > Jerry > >> implementing and easy to fix with little or no risk of breakage. >> >> The proposed patch changes a feature that no one uses. It also imposes the >> relation ship between keepalive and timeout values that is required by the >> RFC and make sense. >> >> You are the final authority, if you say we should just fix the documentation >> than that is fine. >> >> Shoaib >>
