Re: Real Time Traffic Flow Measurement - anybody working on it?

From: Edgar Toernig (froese@gmx.de)
Date: Thu Apr 19 2001 - 16:35:22 EST


Hi,

Michael Clark wrote:
>
> An obvious kernel improvement for userspace meters like NeTraMet would
> be to give libpcap's pcap_read a kernel interface that can return more
> than one packet at a time (the libpcap interface has this capability).

It's already there - the turbo packet interface (PACKET_RX_RING sockopt).
Very nice and fast. Direct transfer to mmapped memory.

> An additional feature for network devices that could support it (not
> sure if this is feasible) would be to switch to an 'interrupt when
> packet buffer full' when in promiscuous mode.

With the RX_RING you can poll a memory location in the mmapped memory
to detect whether there are new packets. You basically only perform
a system call (poll/select) if there's nothing more to do.

Ciao, ET.

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