Date: Thu, 03 Nov 2016 18:04:52 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 214171] [tcp] Out-of-order transmission severely degrades performance Message-ID: <bug-214171-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D214171 Bug ID: 214171 Summary: [tcp] Out-of-order transmission severely degrades performance Product: Base System Version: 10.3-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: noah.bergbauer@tum.de Downloading data from a FreeBSD server over a fast (~700Mbps with 0.1% loss) internet connection that suffers from a lot of packet reordering, I'm seeing very bad transmission rates (~4Mbps whereas Linux gets ~40Mbps on the same connection). Traffic analysis shows that when the client (Windows in my tests) receives out-of-order packets, it first sends out SACKs until the missing packet arr= ives (usually just ~1ms late). Then it ACKs everything normally. Linux reacts to this by just carrying on - after all, no packets were dropp= ed. FreeBSD however appears to react to each SACK immediately and indepentently, assuming that the late packets were actually lost. Because of that, it retransmits them and lowers the transmission rate (I tested with several different congestion control modules and it affects all of them). --=20 You are receiving this mail because: You are the assignee for the bug.=
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