From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: uaca@alumni.uv.es
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: How much we can trust packet timestamping
Date: 30 Dec 2002 13:09:03 +0000 [thread overview]
Message-ID: <1041253743.13097.3.camel@irongate.swansea.linux.org.uk> (raw)
In-Reply-To: <20021230112838.GA928@pusa.informat.uv.es>
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.
Alan
next prev parent reply other threads:[~2002-12-30 12:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-30 11:28 uaca
2002-12-30 13:09 ` Alan Cox [this message]
2002-12-30 13:01 ` uaca
2002-12-30 15:10 ` Alan Cox
2003-01-10 22:07 ` Werner Almesberger
2003-01-11 2:43 ` Alan Cox
2003-01-12 23:04 ` Werner Almesberger
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