Date: Sat, 17 Oct 2015 17:37:40 -0700 From: hiren panchasara <hiren@strugglingcoder.info> To: Randall Stewart <rrs@netflix.com> Cc: FreeBSD Transports <transport@FreeBSD.org> Subject: dupack counter processing (was: Re: The trouble with sack..) Message-ID: <20151018003740.GE87252@strugglingcoder.info> In-Reply-To: <DA8A5844-8F11-42D5-B923-3F329203B867@netflix.com> References: <DA8A5844-8F11-42D5-B923-3F329203B867@netflix.com>
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--ExIO7AL6tcaLjJBF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 10/07/15 at 12:17P, Randall Stewart via freebsd-transport wrote: >=20 > 2) When we recognize a dup-ack we *will not* recognize it if for example = if the rwnd changes even > if new SACK information is reported in the sack blocks. This is due t= o the fact that in non-SACK you don?t > (on purpose) recognize ACK?s where the window changed (since you can?= t really tell if its a > plain window update or a dup-ack).. This means we occasionally miss = out > on stroking the dup-ack counter and getting out of recovery.... Just learned that linux triggers fast recovery right away when it receives a dupack with SACK info that covers at least 3 packets (essentially indicating that 3 packets made it through successfully after a loss/drop event). Here, 3 is tcprexmtthresh for us. This also follows rfc6675. (IsLost()). Cheers, Hiren --ExIO7AL6tcaLjJBF Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQF8BAABCgBmBQJWIunRXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXRBNEUyMEZBMUQ4Nzg4RjNGMTdFNjZGMDI4 QjkyNTBFMTU2M0VERkU1AAoJEIuSUOFWPt/lM9MH/1ZkZJPiVDimJHEKhgzIcwmg /PsqKP1ATuN4fK06aJJGle8YvZFx1EHB+wtAUvMHSAkUH/ZAcZ2w2GV1FA/f8Rt3 npitd1opabQBD/wfwiZxWMCdsYQXf/iWaUVs3lzKpsa5kfAl4HOgPfyL3EhODZpD n9THvUDpSAdTVtwQ6hXouFIqahQMzrnYfBnBiqhfU7HL8VvuPQWJMTWOqLLr4riU lIyobY+e8ndT0Xbp6ogdkgpODjE3cW45AwzaM/UzQfqj/GC42pqim7L01uSP6en9 M57O21rl5iMPFS+tImHcNv2QnY6Ax/2UnpRasWGukvaRx0WzNQ8HRngAStkLTrM= =yLhA -----END PGP SIGNATURE----- --ExIO7AL6tcaLjJBF--
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