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From: John <linux.kernel@free.fr>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: linux-net@vger.kernel.org, netdev@vger.kernel.org,
	Stephen Hemminger <shemminger@linux-foundation.org>,
	linux.kernel@free.fr
Subject: Re: CLOCK_MONOTONIC datagram timestamps by the kernel
Date: Fri, 02 Mar 2007 10:26:57 +0100	[thread overview]
Message-ID: <45E7EDE1.30805@free.fr> (raw)
In-Reply-To: <200703011230.50596.dada1@cosmosbay.com>

Eric Dumazet wrote:

> 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 ;)

By "most" I meant more than 50%.

Has someone tried to measure interrupt latency in Linux? I'd like to 
plot the distribution of network IRQ to interrupt handler latencies.

> If you replace "1 us" by "50 us", then yes, it probably can do it, if "most" 
> means 99%, (not 99.999 %)

I think we need cold, hard numbers at this point :-)

> Anyway, if you want to play, you can apply this patch on top of 
> linux-2.6.21-rc2  (nanosecond resolution infrastructure needs 2.6.21)
> I let you do the adjustments for rt kernel.

Why does it require 2.6.21?

> This patch converts sk_buff timestamp to use new nanosecond infra
> (added in 2.6.21)

Is this mentioned somewhere in the 2.6.21-rc1 ChangeLog?
http://kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.21-rc1

Regards.

  parent reply	other threads:[~2007-03-02  9:46 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 [this message]
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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