From: Stephen Hemminger <shemminger@linux-foundation.org>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: John find <linux.kernel@free.fr>,
linux-net@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: CLOCK_MONOTONIC datagram timestamps by the kernel
Date: Thu, 1 Mar 2007 10:53:48 -0800 [thread overview]
Message-ID: <20070301105348.04c2fd82@freekitty> (raw)
In-Reply-To: <200703011230.50596.dada1@cosmosbay.com>
On Thu, 1 Mar 2007 12:30:50 +0100
Eric Dumazet <dada1@cosmosbay.com> wrote:
> On Wednesday 28 February 2007 17:07, John wrote:
>
> >
> > Consider an idle Linux 2.6.20-rt8 system, equipped with a single PCI-E
> > gigabit Ethernet NIC, running on a modern CPU (e.g. Core 2 Duo E6700).
> > All this system does is time stamp 1000 packets per second.
> >
> > Are you claiming that this platform *cannot* handle most packets within
> > less than 1 microsecond of their arrival?
>
> Yes I claim it.
>
> You expect too much of this platform, unless "most" means 10 % for
> you ;)
>
> If you replace "1 us" by "50 us", then yes, it probably can do it, if "most"
> means 99%, (not 99.999 %)
>
> Anyway, if you want to play, you can apply this patch on top of
> linux-2.6.21-rc2 (nanosecond resolution infrastruture needs 2.6.21)
> I let you do the adjustments for rt kernel.
>
> I compiled it on my i386 machine, and tested it with a patched libpcap/tcpdump
>
> [PATCH] NET : introduce nanosecond time infrastructure and SIOCGSTAMPNS
>
> It appears some machines are *really* fast and that micro second resolution is
> a limiting factor.
>
> This patch converts sk_buff timestamp to use new nanosecond infra (added in
> 2.6.21), and introduces a new ioctl SIOCGSTAMPNS to let applications access
> nanosecond resolution (ie a timespec instead of timeval)
>
>
> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
>
You probably want to add a SO_TIMESTAMPNS setsockopt() value like existing SO_TIMESTAMP
Also use NSEC_PER_USEC rather than hardcoded 1000.
--
Stephen Hemminger <shemminger@linux-foundation.org>
next prev parent reply other threads:[~2007-03-01 18:53 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 ` Stephen Hemminger [this message]
2007-03-01 23:14 ` CLOCK_MONOTONIC datagram timestamps by the kernel 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
-- 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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