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Date:      Wed, 26 Feb 2014 15:28:37 -0800
From:      Scott Long <scott4long@yahoo.com>
To:        Eric van Gyzen <eric@vangyzen.net>
Cc:        FreeBSD Net <freebsd-net@freebsd.org>, Sami Halabi <sodynet1@gmail.com>
Subject:   Re: TSO
Message-ID:  <3F5216B4-2434-45BF-B83C-1D4E1643EAF6@yahoo.com>
In-Reply-To: <530E3211.6020805@vangyzen.net>
References:  <CAEW%2BogYVto3rr6LHVsG4rOuyhXt3ZWbH2kWNk-1kAmwDKROEqg@mail.gmail.com> <530E3211.6020805@vangyzen.net>

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On Feb 26, 2014, at 10:27 AM, Eric van Gyzen <eric@vangyzen.net> wrote:

> On 02/26/2014 11:37, Sami Halabi wrote:
>> Hi,
>> I'm reading (almost) all mailing emails in mailig list...
>>=20
>> Almost every / many problem in network performancr / packets loss =
ended up
>> suggesting disabling TSO.
>>=20
>> 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?
>=20
> In some cases, I have disabled TSO to [successfully] work around a bug
> in a particular NIC's firmware or hardware, usually a low-end =
"desktop"
> gigabit NIC.
>=20

The same thing happened 10-15 years ago with TCP Checksum offload.  =
Hardware
support appeared, software support appeared, problems cropped up in =
both, and
it became an iterative process of identifying, disabling, and fixing.  =
It=92s now a solid
feature that works without question (though there was a paper recently =
claiming
that hardware CSUM offload doesn=92t matter anymore for performance; =
that=92s a
different topic of discussion).

Scott





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