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.
prev parent reply other threads:[~2007-02-28 18:22 UTC|newest]
Thread overview: 34+ 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]
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