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From: Stephen Hemminger <shemminger@linux-foundation.org>
To: John <linux.kernel@free.fr>
Cc: linux-net@vger.kernel.org, netdev@vger.kernel.org, linux.kernel@free.fr
Subject: Re: CLOCK_MONOTONIC datagram timestamps by the kernel
Date: Wed, 28 Feb 2007 10:22:31 -0800	[thread overview]
Message-ID: <20070228102231.05461589@localhost> (raw)
In-Reply-To: <45E585AD.8050704@free.fr>

On Wed, 28 Feb 2007 14:37:49 +0100
John <linux.kernel@free.fr> wrote:

> John wrote:
> 
> > I know it's possible to have Linux timestamp incoming datagrams as soon
> > as they are received, then for one to retrieve this timestamp later with
> > an ioctl command or a recvmsg call.
> 
> Has it ever been proposed to modify struct skb_timeval to hold 
> nanosecond stamps instead of just microsecond stamps? Then make the 
> improved precision somehow available to user space.
> 

I am playing with a couple of possible future changes.
1. Change skb timestamp to be a timespec instead of timeval, for ABI
   compatiablity the existing SO_TIMESTAMP has to stay microseconds,
   but add a new SO_TIMESPEC to get the nanosecond version.

   The change gets non trivial because of other uses of timestamp (like vegas)
   so I gave up for now.

2. Use hardware receive timestamp in Yukon2 to put actual receive time
   into skb timestamp.  Works, but still figuring out how to manage
   clock skew/resync.

  parent reply	other threads:[~2007-02-28 18:22 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-28 10:18 CLOCK_MONOTONIC datagram timestamps by the kernel John
2007-02-28 13:37 ` John
2007-02-28 13:55   ` Eric Dumazet
2007-02-28 14:23     ` John
2007-02-28 14:55       ` Eric Dumazet
2007-02-28 16:07         ` John
2007-03-01 10:03           ` Evgeniy Polyakov
2007-03-01 11:30           ` Eric Dumazet
2007-03-01 15:54             ` Stephen Hemminger
2007-03-01 16:13               ` Eric Dumazet
2007-03-02 14:38               ` [PATCH] NET : convert network timestamps to ktime_t Eric Dumazet
2007-03-02 16:27                 ` Stephen Hemminger
2007-03-02 21:02                 ` Stephen Hemminger
2007-03-02 22:46                   ` Eric Dumazet
2007-03-05  0:19                     ` David Miller
2007-03-05  6:56                       ` Eric Dumazet
2007-03-05  7:40                         ` Eric Dumazet
2007-03-05  8:00                           ` David Miller
2007-03-05  8:21                             ` Eric Dumazet
2007-03-05  8:49                               ` David Miller
2007-03-08 14:17                 ` [PATCH] NET : Introduce SIOCGSTAMPNS ioctl to get timestamps with nanosec resolution Eric Dumazet
2007-03-08 16:28                   ` Patrick McHardy
2007-03-08 16:42                     ` Eric Dumazet
2007-03-08 16:45                       ` Patrick McHardy
2007-03-09  4:39                   ` David Miller
2007-03-09 18:39                   ` [PATCH] NET : Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support Eric Dumazet
2007-03-09 22:17                     ` David Miller
2007-03-01 18:53             ` CLOCK_MONOTONIC datagram timestamps by the kernel Stephen Hemminger
2007-03-01 23:14               ` Eric Dumazet
2007-03-01 23:34                 ` Stephen Hemminger
2007-03-02  0:56                   ` Eric Dumazet
2007-03-02  9:26             ` John
2007-03-02 10:11               ` Eric Dumazet
2007-02-28 18:22   ` Stephen Hemminger [this message]
  -- strict thread matches above, loose matches on Subject: below --
2007-02-25 21:29 John
2007-02-26 10:26 ` John
2007-02-26 12:20   ` Andi Kleen
2007-02-26 14:17     ` John
2007-02-28 11:23       ` John

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