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Date: Fri, 25 May 2012 17:17:42 +0100 From: Dave Taht <dave.taht@...il.com> To: Chris Friesen <chris.friesen@...band.com> Cc: Srećko Jurić-Kavelj <srecko.juric-kavelj@....hr>, netdev@...r.kernel.org Subject: Re: Using jiffies for tcp_time_stamp? On Fri, May 25, 2012 at 4:58 PM, Chris Friesen <chris.friesen@...band.com> wrote: > 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. I would be interested in someone doing that experiment in light of the codel work. > > Chris > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Dave Täht SKYPE: davetaht US Tel: 1-239-829-5608 http://www.bufferbloat.net -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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