[ntp:questions] Effect of Gigabit Interrupt coalescence on ntp timing

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David Malone wrote:
> FWIW, I think the Intel NICs in question support some 1588
>  features, but I don't think you can get a timestamp for
>  every packet. Or, when I looked at the code/docs,
>  I couldn't figure out how to do it.
>  If someone knows otherwise, I'd like to be corrected ;-)

It depends on the MAC,
 IIRC, the i350 & 82580 can, and the 82599 & 82576 can't.

FYI:  \igb-3.4.7\src\igb_main.c
#ifdef IGB_PER_PKT_TIMESTAMP
	/*
	 * Per-packet timestamping only works if all packets are
	 * timestamped, so enable timestamping in all packets as
	 * long as one rx filter was configured.
	 */
	if ((hw->mac.type >= e1000_82580) && tsync_rx_ctl) {
		tsync_rx_ctl = E1000_TSYNCRXCTL_ENABLED;
		tsync_rx_ctl |= E1000_TSYNCRXCTL_TYPE_ALL;
	}
#endif
<http://sourceforge.net/projects/e1000/files/igb%20stable/3.4.7/igb-3.4.7.tar.gz/download>


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