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[86.66.237.171]) by mx.google.com with ESMTPS id j6sm15901970wiy.4.2012.08.05.10.35.14 (version=SSLv3 cipher=OTHER); Sun, 05 Aug 2012 10:35:15 -0700 (PDT) From: Eric Dumazet To: Richard Scheffenegger In-Reply-To: <1344187557.9299.1610.camel@edumazet-glaptop> References: <1344048299-26267-1-git-send-email-dave.taht@bufferbloat.net> <1344062738.9299.1453.camel@edumazet-glaptop><501D99C4.20902@pollere.com> <7EB59257-1A8E-4567-8AD3-5016594565CC@gmail.com> <1344144623.9299.1557.camel@edumazet-glaptop> <4A256974B5054317913BC067C4E5FAE1@srichardlxp2> <1344187557.9299.1610.camel@edumazet-glaptop> Content-Type: text/plain; charset="UTF-8" Date: Sun, 05 Aug 2012 19:35:12 +0200 Message-ID: <1344188112.9299.1614.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Cc: codel@lists.bufferbloat.net Subject: Re: [Codel] [RFC PATCH] codel: ecn mark at target X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 Aug 2012 17:35:18 -0000 On Sun, 2012-08-05 at 19:26 +0200, Eric Dumazet wrote: > It could be a flaw in linux implementation, I admit we had so many bugs > that it could very well be still buggy. And at first glance, the following tcpdump seems suspect : We can see all ACK are delayed by about 40 ms 19:30:54.367739 IP (tos 0x3,CE, ttl 64, id 52620, offset 0, flags [DF], proto TCP (6), length 1500) 172.30.42.19.50341 > 172.30.42.18.50103: Flags [.], seq 156841:158289, ack 1, win 115, options [nop,nop,TS val 3115533 ecr 111212487], length 1448 19:30:54.406063 IP (tos 0x0, ttl 64, id 62099, offset 0, flags [DF], proto TCP (6), length 52) 172.30.42.18.50103 > 172.30.42.19.50341: Flags [.E], cksum 0xac88 (incorrect -> 0xe2b7), ack 158289, win 551, options [nop,nop,TS val 111212491 ecr 3115533], length 0 19:30:54.407212 IP (tos 0x3,CE, ttl 64, id 52621, offset 0, flags [DF], proto TCP (6), length 1500) 172.30.42.19.50341 > 172.30.42.18.50103: Flags [P.W], seq 158289:159737, ack 1, win 115, options [nop,nop,TS val 3115573 ecr 111212491], length 1448 19:30:54.446057 IP (tos 0x0, ttl 64, id 62100, offset 0, flags [DF], proto TCP (6), length 52) 172.30.42.18.50103 > 172.30.42.19.50341: Flags [.E], cksum 0xac88 (incorrect -> 0xdce3), ack 159737, win 551, options [nop,nop,TS val 111212495 ecr 3115573], length 0 19:30:54.448209 IP (tos 0x3,CE, ttl 64, id 52622, offset 0, flags [DF], proto TCP (6), length 1500) 172.30.42.19.50341 > 172.30.42.18.50103: Flags [.W], seq 159737:161185, ack 1, win 115, options [nop,nop,TS val 3115613 ecr 111212495], length 1448 19:30:54.486057 IP (tos 0x0, ttl 64, id 62101, offset 0, flags [DF], proto TCP (6), length 52) 172.30.42.18.50103 > 172.30.42.19.50341: Flags [.E], cksum 0xac88 (incorrect -> 0xd70f), ack 161185, win 551, options [nop,nop,TS val 111212499 ecr 3115613], length 0 19:30:54.487443 IP (tos 0x3,CE, ttl 64, id 52623, offset 0, flags [DF], proto TCP (6), length 1500) 172.30.42.19.50341 > 172.30.42.18.50103: Flags [.W], seq 161185:162633, ack 1, win 115, options [nop,nop,TS val 3115653 ecr 111212499], length 1448 19:30:54.526069 IP (tos 0x0, ttl 64, id 62102, offset 0, flags [DF], proto TCP (6), length 52) 172.30.42.18.50103 > 172.30.42.19.50341: Flags [.E], cksum 0xac88 (incorrect -> 0xd13b), ack 162633, win 551, options [nop,nop,TS val 111212503 ecr 3115653], length 0 19:30:54.527241 IP (tos 0x2,ECT(0), ttl 64, id 52624, offset 0, flags [DF], proto TCP (6), length 1500) 172.30.42.19.50341 > 172.30.42.18.50103: Flags [.W], seq 162633:164081, ack 1, win 115, options [nop,nop,TS val 3115693 ecr 111212503], length 1448 19:30:54.566049 IP (tos 0x0, ttl 64, id 62103, offset 0, flags [DF], proto TCP (6), length 52) 172.30.42.18.50103 > 172.30.42.19.50341: Flags [.], cksum 0xac88 (incorrect -> 0xcba7), ack 164081, win 551, options [nop,nop,TS val 111212507 ecr 3115693], length 0 19:30:54.567809 IP (tos 0x3,CE, ttl 64, id 52625, offset 0, flags [DF], proto TCP (6), length 1500) 172.30.42.19.50341 > 172.30.42.18.50103: Flags [.], seq 164081:165529, ack 1, win 115, options [nop,nop,TS val 3115733 ecr 111212507], length 1448 19:30:54.606067 IP (tos 0x0, ttl 64, id 62104, offset 0, flags [DF], proto TCP (6), length 52) 172.30.42.18.50103 > 172.30.42.19.50341: Flags [.E], cksum 0xac88 (incorrect -> 0xc593), ack 165529, win 551, options [nop,nop,TS val 111212511 ecr 3115733], length 0 19:30:54.607088 IP (tos 0x2,ECT(0), ttl 64, id 52626, offset 0, flags [DF], proto TCP (6), length 1500) 172.30.42.19.50341 > 172.30.42.18.50103: Flags [.W], seq 165529:166977, ack 1, win 115, options [nop,nop,TS val 3115773 ecr 111212511], length 1448 19:30:54.646056 IP (tos 0x0, ttl 64, id 62105, offset 0, flags [DF], proto TCP (6), length 52) 172.30.42.18.50103 > 172.30.42.19.50341: Flags [.], cksum 0xac88 (incorrect -> 0xbfff), ack 166977, win 551, options [nop,nop,TS val 111212515 ecr 3115773], length 0 19:30:54.648105 IP (tos 0x3,CE, ttl 64, id 52627, offset 0, flags [DF], proto TCP (6), length 1500) 172.30.42.19.50341 > 172.30.42.18.50103: Flags [.], seq 166977:168425, ack 1, win 115, options [nop,nop,TS val 3115813 ecr 111212515], length 1448