From mboxrd@z Thu Jan 1 00:00:00 1970 From: Samuel Jero Date: Fri, 26 Apr 2013 18:58:39 +0000 Subject: Re: [RFC][PATCH] tfrc: Correct 2nd Loss Interval Handling Message-Id: <517ACE5F.4080609@ohio.edu> MIME-Version: 1 Content-Type: multipart/mixed; boundary="------------enig6756107ED47B73EFAAB6E46B" List-Id: References: <516C3031.4050405@ohio.edu> In-Reply-To: <516C3031.4050405@ohio.edu> To: dccp@vger.kernel.org --------------enig6756107ED47B73EFAAB6E46B Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Gerrit, >> >> [1] http://www.sjero.net/software/dccp/images/dccp_ccid3_2nd_loss_inte= rval_bug.png >> > Thank you for the patch and the detailed explanation. Are there before/= after test results > relative to [1] which indicate that the sharp bend in the diagram is no= w gone, or any other > notable improvements with this fix? An example of this same test with this fix applied is at [2]. Of course f= or this bug to show up as dramatically as in [1] we need to get a single loss while the conne= ction is sending very slowly and then not receive another loss until much later. It's much more instructive to look at the Loss Event Rate Options the DCC= P receiver sends.=20 (DCCP loss event rate options are sent as 1/loss_rate so a loss rate opti= on of 33 represents a loss rate of 1/33---1 packet out of every 33 sent) In the buggy case we see Feedback packets with these options (each line i= s a feedback packet) CCID3 Loss Event Rate: 0 (or max) CCID3 Loss Event Rate: 0 (or max) CCID3 Loss Event Rate: 33 CCID3 Loss Event Rate: 33 CCID3 Loss Event Rate: 33 CCID3 Loss Event Rate: 33 CCID3 Loss Event Rate: 33 .... CCID3 Loss Event Rate: 33 CCID3 Loss Event Rate: 33 CCID3 Loss Event Rate: 18191 CCID3 Loss Event Rate: 18191 While with my fix, we see this: CCID3 Loss Event Rate: 0 (or max) CCID3 Loss Event Rate: 0 (or max) CCID3 Loss Event Rate: 0 (or max) CCID3 Loss Event Rate: 434 CCID3 Loss Event Rate: 434 ... CCID3 Loss Event Rate: 434 CCID3 Loss Event Rate: 434 CCID3 Loss Event Rate: 442 CCID3 Loss Event Rate: 467 CCID3 Loss Event Rate: 491 CCID3 Loss Event Rate: 517 CCID3 Loss Event Rate: 545 CCID3 Loss Event Rate: 572 CCID3 Loss Event Rate: 603 CCID3 Loss Event Rate: 637 You'll notice that with this fix, the loss event rate option starts incre= asing (i.e. the loss event RATE decreases) after a while. This means that the 2nd loss interval has = become large enough to=20 start effecting the loss event rate. In the buggy case, we have to wait u= ntil that 2nd loss interval is closed by the 2nd loss before it can effect the rate, resulting in the= large jump seen above. [2] http://www.sjero.net/software/dccp/images/dccp_ccid3_2nd_loss_interva= l_fixed.png Samuel Jero Masters Student Computer Science Internetworking Research Group Ohio University sj323707@ohio.edu --------------enig6756107ED47B73EFAAB6E46B Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with undefined - http://www.enigmail.net/ iQIcBAEBAgAGBQJRes5kAAoJEPUrqO1w+kIcWhkP/2eWg6NOZQG7Iqr0n6OK62Hc YmZNMDFaqQK8p2/CmRqaTEdexUFipGFe3hdK3kLEcWBnKn5MsqxI0mLkuowDqcob oSLvbySMrbKwLwjCeTfBk+8rHNCF0rh4WwjdSto+XqDbdRHRTQxVCTCJP1DpFJlF mkaWiboo2T2pb2Wa/PISZ2Ewm+SY7RMMQvKxTSPeoFrDu2bUW8c99i6Elk73l0/G IBHjNSwFUGfuRdDbdFWT34NLpxE43GU4zehOJTakHrfmlhJjYhLIxeoHi8EZQfxp GNbRhcYwYZ/TRjSgqPpxXsBZWHMg4sgRDCjU7hRXSErMpgkRDk2cd66j2j2QgmTv wkvAEFUZqLrvdaMCd/Ni8Vcb1FBNRqKdBWM7fO17LSfw1u5wqUGAiRIPK5Gi5Cia jzeDHdlJ0CouILT+14Q1tTL4yUZBBtjGXBuABR6MwVPloNvR+EdhzAJLiaHgQykl RFENDAuARpP43I0ZMqA0g0cklGcLbevwA6Tf7bbrfBxNH0dZVU3hDyn6QibDFBjB HV006pHhagoLWqY8KDkoqUliPvXSbQLgHWCnhEJVxAQ2cppI8REZAFWGfr+gdRmL +sR5CcF1KiG6mOQlJjYIVwa3KIn/pyUtpbzudx409vHE/UuV4ZJ+l2rtG3HxdKZS SpFJvNUK1l25vI64xw4Z =fA+Y -----END PGP SIGNATURE----- --------------enig6756107ED47B73EFAAB6E46B--