[Bloat] Re: calculating baseline latency properly?

David Collier-Brown davec-b at rogers.com
Mon Jan 9 17:16:26 EST 2012


Dave Taht wrote:
> In measuring ping RTT rather than arrival time elsewhere (which I plan
> to do with RTP at some point), there's actually two variables in play
> send and return time...
>
> So should a RTT latency under load calculation remove the baseline latency
> thusly:
>
> latency_improvement =
>   (ping_RTT - baseline_ping_rtt) / (new_ping_RTT - baseline_ping_rtt)
>
> factor 344 improvement
>
> OR keep it:
>
> latency_improvement =
>   (ping_RTT) / (new_ping_RTT)
>
> factor 180 improvement...
>
> or would there be another way to compensate for it that made sense?
>   
If the improvement in the *baseline* ping times is part of the
improvement you're seeing, it's
fair to include it in the calculation.  In other words, if it's causal,
it's golden.  If you're unsure, leave it out.

--dave (random capacity-planning guy) c-b

-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb at spamcop.net           |                      -- Mark Twain
(416) 223-8968




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