[Tech] What I don't understand... (simulations)

[Michael Rogers]

toad wrote:
> I don't understand why slow nodes don't pull down the throttle. Is the
> throttle using the same parameters as on the network proper?

No, the simulated throttle is much simpler - no RTT measurement, one 
throttle for all inserts and requests rather than 4 separate throttles. 
To be honest I'm not sure RTT measurement makes much sense when each 
search follows a different path, but I'm willing to emulate the current 
behaviour more closely if it would be useful.

> The thing is, it seems to me that this is exactly what is happening on
> the main network - average bandwidth usage is very low, precisely
> because the throttles aren't starting many requests.

I don't think the simulations show low bandwidth usage, but I'll check.

> Do the simulations approximate the current shouldRejectRequest()
> behaviour reasonably well? In particular do they emulate the predictive
> bandwidth allocation code?

Bandwidth prediction and ping time aren't simulated, I'm afraid - 
shouldRejectRequest() is just based on a running average of the 
bandwidth/congestion delay (ie how long messages are delayed beyond 
their coalescing deadlines).

I'm happy to make the simulations more realistic, but there's a tradeoff 
between testing new features (eg token passing) and simulating existing 
features accurately - I'm happy to do either, so let me know which would 
be more useful.

Cheers,
Michael