Re: [net-next 11/13] igb: Update PTP function names/variables and locations.

On Thu, Aug 23, 2012 at 06:00:37PM +0000, Keller, Jacob E wrote:

quoted

Right now the time stamping is being equated with the clock functions, but
it really should be decoupled. The 82580 can time stamp every received
packet, which can be interesting for performance monitoring, even without
PTP (and adding *that* would be a useful change).

The timestamp all does not really work with the ptp clock features
gone, because you don't have the clock. You can't equate the time
values of the packets when the clock isn't synched to something
meaningful. Yes that does not require PTP adjustment functions, but
it does require the SYSTIME setup and some method to get the clock
correct, which currently is only done in the PTP init sequence.

Relative, high resolution time stamps can be interesting all by
themselves. That is why wireshark has a whole menu of timing choices
including relative since start, inter-packet, and so on.

Timestamp all packets also can cause a performance hit when used with certain workloads.

Only when enabled.

ixgbe hardware is (currently) even more closely synched with PTP for the register bits so it does make some sense for ixgbe to remain the way it is. Right now the igb features are partially synched (even before this change) in odd ways. The time values returned when PHC information is disabled are basically only useful for comparing between themselves, not with any meaningful clock on the device.

Yes, I agree that igb is a bit oddly synced WRT clock and time
stamping. I would welcome a change to let it have HW time stamping as
an independent feature.

Thanks,
Richard