[ntp:hackers] NTP two-step on-wire protocol
dwmalone at maths.tcd.ie
Mon Jul 23 20:13:01 UTC 2007
On Mon, Jul 23, 2007 at 03:04:37AM +0000, David L. Mills wrote:
> I'm more worried that the modern complexity in NIC operations may nix
> the whole idea.
While modern NICs rarely interrupt on every packet, some of them
do allow nice features like requestion an interrupt on a particular
packet. I've used this to measure the CSMA/CA delay in 802.11
networks on Atheros based cards, and get results that are good to
a handful microseconds without having to work too hard.
One interesting down side to adding an option that requests an
immediate interrupt after packer transmission is that it is quite
possible to swamp a CPU by causing interrupts for every packet.
Shouldn't be a problem for the occasional NTP packet though.
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