Re: How much we can trust packet timestamping

[uaca@alumni.uv.es]

On Mon, Dec 30, 2002 at 01:09:03PM +0000, Alan Cox wrote:
> On Mon, 2002-12-30 at 11:28, uaca@alumni.uv.es wrote:
> > Hi all
> > 
> > IMHO The problem is quite complicated because
> > 
> > + common hardware is not designed for real time:
> > 
> > 	- sends multiple PDUs within one interrupt, and can be delayed
> > 	- Host adapter bus & infraestructure is not designed to garantee latency
> >   	etc...
> 
> The packet can be timestamped by the hardware receiving as well as by
> the kernel netif_rx code. This is actually intentional and there is
> hardware that supports doing IRQ raise time sampling which the driver
> can then use to get very accurate data.

Thanks Alan

Anybody know about a Linux driver that supports doing IRQ raise time
sampling? any doc/pointer/suggestion would be greatly appreciated

Thanks in advance

	Ulisses
                Debian GNU/Linux: a dream come true
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