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Date: Sat, 06 Sep 2014 00:43:29 +0200
From: Hans Petter Selasky <hps@selasky.org>
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To: Rick Macklem <rmacklem@uoguelph.ca>
Subject: Re: [RFC] Patch to improve TSO limitation formula in general
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Cc: freebsd-net@freebsd.org, Eric Joyner <ricera10@gmail.com>,
 FreeBSD Current <freebsd-current@freebsd.org>, Scott Long <scottl@freebsd.org>,
 Jack F Vogel <jfvogel@gmail.com>
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On 09/06/14 00:09, Rick Macklem wrote:
> Hans Petter Selesky wrote:
>> On 09/05/14 23:19, Eric Joyner wrote:
>>> There are some concerns if we use this with devices that ixl
>>> supports:
>>>
>>> - The maximum fragment size is 16KB-1, which isn't a power of 2.
>>>
>>
>> Hi Eric,
>>
>> Multiplying by powers of two are more fast, than non-powers of two.
>> So
>> in this case you would have to use 8KB as a maximum.
>>
> Well, I'm no architecture expert, but I really doubt the CPU delay of a
> non-power of 2 multiply/divide is significant related to doing smaller
> TSO segments. Long ago (as in 1970s) I did work on machines where shifts
> for power of 2 multiply/divide was preferable, but these days I doubt it
> is going to matter??
>

Hi,

You also need to patch LAGG and VLAN drivers?

--HPS