[time-nuts] Google NTP Servers and smearing leap seconds...
shalimr9 at gmail.com
shalimr9 at gmail.com
Sun Sep 18 11:32:43 UTC 2011
Actually, if you pay attention, it probably only takes your bank a few uS to debit your account when you write a check. It takes 5 days to credit it when you receive one.
A perfect example of asymmetric processing :)
Sent from my BlackBerry Wireless thingy while I do other things...
From: "Tom Holmes" <tholmes at woh.rr.com>
Sender: time-nuts-bounces at febo.com
Date: Fri, 16 Sep 2011 21:25:46
To: 'Discussion of precise time and frequency measurement'<time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts at febo.com>
Subject: Re: [time-nuts] Google NTP Servers and smearing leap seconds...
All this fuss over microseconds being worth billions and it still takes a
bank 5 days to find out if the check I wrote is good?
Where's a good manure scoop when you need one?
Tom Holmes, N8ZM
Tipp City, OH
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Bob Paddock
> Sent: Friday, September 16, 2011 7:50 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Google NTP Servers and smearing leap seconds...
> On Fri, Sep 16, 2011 at 2:36 PM, Hal Murray <hmurray at megapathdsl.net>
> > xaos at darksmile.net said:
> >> You can forget Wall St. firms and Banks for starters.
> >> They need sub-microsecond accurate timing as some instruments (Forex)
> >> moving to <10 microsecond latency from order entry to order ack.
> > 10 microsecond latency doesn't say anything about how accurate the time
> > to be.
> > Does anybody have a good URL on the accuracy requirements of banks
> > stock markets? I expect there are both legal and technical issues. I'd
> > to understand them separately
> There are some big names in Banking and Stocks behind the
> Advanced Message Queuing Protocol (AMQP):
> Actually Time Nut Grade measurements are not addressed at this level
> to my knowledge.
> <p><b>Round Trip</b>: The term round trip refers to the
> process of a peer sending a command to its partner and
> receiving confirmation that the command is complete. Round
> trips are necessary for synchronization of world views,
> however, it is not necessary for a client to wait and do
> nothing while a round trip occurs or only deal with a single
> round trip at a time.</p>
> <p><b>Round Trip Time (RTT)</b>: The term RTT refers to the
> time taken to complete a round trip. This is described with
> the following formula:</p>
> RTT = 2*latency_network + latency_processing
> <p>Note that RTT at the execution layer differs from RTT at
> the network layer. At the network layer the processing
> latency is zero resulting in an RTT of twice the network
> latency. At the execution layer the processing time becomes
> significant if, for example, processing the command requires
> sending data to disk. This would be the case with durable
> messages and the RTT would then include the Broker's disk
> > but I won't be surprised if they are thoroughly
> > tangled.
> There is also the even more obscure 0MQ:
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