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

Ulf Samuelsson ulf at invalid.com
Wed Dec 19 09:47:24 UTC 2012

On 2012-12-19 04:07, E-Mail Sent to this address will be added to the 
BlackLists wrote:
> 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

In the header files, yes.
Restrict your search to *.c and you will find NADA...


>>   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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