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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