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From: Chris Friesen <chris.friesen@genband.com>
To: "Srećko Jurić-Kavelj" <srecko.juric-kavelj@fer.hr>
Cc: netdev@vger.kernel.org
Subject: Re: Using jiffies for tcp_time_stamp?
Date: Fri, 25 May 2012 09:58:40 -0600	[thread overview]
Message-ID: <4FBFAC30.8050508@genband.com> (raw)
In-Reply-To: <CAACrLC2CXU-DNeonWQGJTfX53ssm_asK7WQrFuWRBB77cg-YdA@mail.gmail.com>

On 05/22/2012 11:21 AM, Srećko Jurić-Kavelj wrote:

> By looking at the code it's clear that the time stamping is done with
> jiffies, and my kernel has CONFIG_HZ=100.
>
> I understand that this is for performance reasons (and the RTT
> smoothing filter is implemented with bit shifting operations), but
> would using a more precise time stamp have significant impact on
> performance? Since RTT is used to compute RTO, wouldn't there be any
> benefits of having more accurate estimate of this value?

I don't know if it would make any difference to the tcp algorithms, but 
certainly on some architectures you can get a fast and accurate hardware 
timestamp.

Chris

  reply	other threads:[~2012-05-25 15:58 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-22 15:45 Using jiffies for tcp_time_stamp? Srećko Jurić-Kavelj
2012-05-22 16:21 ` David Miller
2012-05-22 17:21 ` Srećko Jurić-Kavelj
2012-05-25 15:58   ` Chris Friesen [this message]
2012-05-25 16:17     ` Dave Taht
2012-05-25 16:23       ` Srećko Jurić-Kavelj
2012-05-25 16:54         ` Eric Dumazet
2012-05-25 18:35           ` Srećko Jurić-Kavelj
2012-05-25 19:00             ` Eric Dumazet

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