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

Ulf Samuelsson ulf at invalid.com
Wed Dec 19 00:05:50 UTC 2012

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<Null at BlackList.Anitech-Systems.invalid> 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
The latest version of the igb driver does not support launch time 
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

Rx Timestamp is supported, but that is not the issue here.

Best Regards, Ulf Samuelsson

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