Re: [Linuxptp-users] Fw: “Resource temporarily unavailable” errors during flood ping test

[Keller, J. E <jac...@in...>]

> -----Original Message-----
> From: Richard Cochran [mailto:ric...@gm...]
> Sent: Tuesday, October 30, 2012 10:24 AM
> To: Keller, Jacob E
> Cc: lin...@li...
> Subject: Re: [Linuxptp-users] Fw: “Resource temporarily unavailable”
> errors during flood ping test
> 
> On Tue, Oct 30, 2012 at 09:54:30AM -0700, Jacob Keller wrote:
> >
> > I believe the true correct answer is to completely re-architect the
> > tx_hwtstamp to be asynchronous, so that it just waits until it receives
> > the timestamp for a complete sequence of events. That design is
> > significantly more difficult to write though.
> 
> But even if we did that way, it would not really be a better
> solution. Think about your own Intel cards. They would end up missing
> Tx time stamps and possibly mixing them up due to the hardware
> limitation of having a Tx time stamp FIFO of depth one.
> 
> And it is not just Intel cards that have this issue. I think the
> majority of the current hardware offerings all have this same
> limitation.  So we really must wait for the Tx time stamp after
> sending an event message before going on with the protocol, simply
> to function on most of the hardware out there.
> 
> Thanks,
> Richard

I think we can get PTP4l to work right even under those scenarios, but right now it is horribly annoying that practically everyone has to change the value if they ever have stress when ptp is running.

I like the idea of architecting it to use select and a delay value, so I'll try to see how difficult that would be.

- Jake