Re: [PATCH net-next v3 08/11] net: ethernet: ti: cpts: move rx timestamp processing to ptp worker only

From: Richard Cochran
Date: Tue Mar 24 2020 - 12:54:21 EST


On Tue, Mar 24, 2020 at 05:34:34PM +0200, Grygorii Strashko wrote:
> I tested both ways and kept this version as i'v not seen any degradation,
> but, of course, i'll redo the test (or may be you can advise what test to run).

Measure the time delay from when the frame arrives in the stack until
that frame+RxTimestamp arrives in the application. I expect the round
about way via kthread takes longer.

> My thoughts were - network stack might not immediately deliver packet to the application

The network stack always delivers the packet, but you artificially
delay that delivery by calling netif_receive_skb() later on from
cpts_match_rx_ts().

> and PTP worker can be tuned (pri and smp_affinity),

That won't avoid the net softirq.

> resulted code will be more structured,

I am afraid people will copy this pattern in new drivers. It really
does not make much sense.

Thanks,
Richard