Date: Wed, 26 Feb 2014 10:07:36 -0800 From: John-Mark Gurney <jmg@funkthat.com> To: Sami Halabi <sodynet1@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: TSO Message-ID: <20140226180736.GV92037@funkthat.com> In-Reply-To: <CAEW%2BogYVto3rr6LHVsG4rOuyhXt3ZWbH2kWNk-1kAmwDKROEqg@mail.gmail.com> References: <CAEW%2BogYVto3rr6LHVsG4rOuyhXt3ZWbH2kWNk-1kAmwDKROEqg@mail.gmail.com>
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Sami Halabi wrote this message on Wed, Feb 26, 2014 at 19:37 +0200: > I'm reading (almost) all mailing emails in mailig list... > > Almost every / many problem in network performancr / packets loss ended up > suggesting disabling TSO. > > I wonder why.. Is it a bug in the implementation? Or bybdesign? > What are the usecases that TSO is needed? Myabe it should be disabled bt > default? It looks like most of the problems are in drivers that don't handle packets with a large number of segments properly... The problem is that some drivers limit to how segments a packet can be broken into, and then if they receive such a packet, instead of doing their darnest to deliver it, they drop it... There are some patches that help address the issue... Drivers should complain more loudly when a packet gets dropped by the driver, since it is likely that the OS may retry the same packet, just to have it fail, though sometimes it'll try a different set, and it might go through, so all the user may notice is a slight lag if they notice anything at all... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."
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