[RFC] Patch to improve TSO limitation formula in general

Hans Petter Selasky hps at selasky.org
Fri Sep 5 22:43:34 UTC 2014


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



More information about the freebsd-net mailing list