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Date: Sat, 02 Dec 2017 07:20:56 -0500
From: Joe Buehler <aspam@cox.net>
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To: "K. Macy" <kmacy@freebsd.org>
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Subject: Re: netmap / LINUX realtime / ixgbevf: huge RX latencies
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K. Macy wrote:

> HEAD or 11?

I'm not quite sure what the question means but there is this in the
netmap code:

./net/netmap.h:42:#define	NETMAP_API	11		/* current API version */

LINUX kernels nowadays can timestamp frames when they arrive from the
NIC.  I made a trivial patch to the netmap driver to turn this on and
also pass the timestamp to user space, and will pass on the changes.  I
am doing frame latency measurements and this simple change eliminated a
*whole* lot of noise in the measurements.

Joe Buehler