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From: Dimitris Michailidis <dm@chelsio.com>
To: David Miller <davem@davemloft.net>
Cc: therbert@google.com, eric.dumazet@gmail.com, netdev@vger.kernel.org
Subject: Re: [PATCH net-next-2.6] net: Consistent skb timestamping
Date: Sun, 16 May 2010 11:30:50 -0700	[thread overview]
Message-ID: <4BF039DA.3020207@chelsio.com> (raw)
In-Reply-To: <20100515.235635.63009445.davem@davemloft.net>

David Miller wrote:

> The real fix is to make the devices less stupid and give us timestamps
> directly, and thanks to things like PTP support in hardware that's
> actually more and more of a reality these days.

For cxgb4 a timestamp is written into Rx descriptors for each received 
packet.  The value comes from a TSC-like cycle counter.  The raw timestamp 
is very cheap to get, its value converted to system ktime a bit less so 
though not too bad.  It would be nicer though if the stack could hint the 
driver whether it should do the conversion at all.  Maybe export 
netstamp_needed and add an inline wrapper to read it?


      reply	other threads:[~2010-05-16 18:31 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-06 12:01 [PATCH net-next-2.6] net: Consistent skb timestamping Eric Dumazet
2010-05-06 15:12 ` Tom Herbert
2010-05-06 15:37   ` Eric Dumazet
2010-05-06 16:14     ` Eric Dumazet
2010-05-16  6:57       ` David Miller
2010-05-16  6:56   ` David Miller
2010-05-16 18:30     ` Dimitris Michailidis [this message]

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