[ntp:questions] A proposal to use NIC launch time support to improve NTP

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Wed Dec 19 03:07:02 UTC 2012


Ulf Samuelsson wrote:> BlackLists wrote:
>> Ulf Samuelsson wrote:
>>> In my proposal, I add a new flag to "socket.c:sendto".
>>> While the launchtime is proposed to configurable using
>>>  Kconfig, this adds a small performance penalty to every
>>>  other packet sent over Ethernet.
>>>
>>> An alternative would be to extend the kernel with a new
>>>  syscall, which would not impose a penalty to "sendto".
>>> Then "sendto" would not be burdened with "launchtime"
>>>  which for most applications is unneeded.
>>> I do have a feeling that proposing adding syscall's
>>>  is not the easy route forward.
>>
>> Isn't it already supported in kernels 2.6.30 and above?
>>
>> I'd start by looking at how the 1588 PTP group is already
>>  supporting the features of those Ethernet MACs.
>>   {82576, 82580, i210, i211, i350 ? and perhaps
>>     IXP46X, 82574, 82575, 80579, 82599 ?}
>>
>> I think TI also has a chip with similar features?
>>
>
> Launch time is only supported H/W wise in the i210/11.
>  Not in earlier chips.
> The latest version of the igb driver does not support launch time

E1000_TQAVCTRL_LAUNCH_ARB, E1000_TQAVCTRL_LAUNCH_TIMER_ENABLE ?


>  so I do not see how the kernel can support this.
> Please state where the launch time code is in the kernel,
>  if you believe otherwise.
>
> Rx Timestamp is supported, but that is not the issue here.

I'm sorry, I must have been mistaken.


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