Ramp-up is an optional procedure that gradually increases the rate that a rate limiter allows — from a small value at the beginning of the ramp, typically when a node starts, up to the configured maximum.

This allows time for events such as Just-In-Time compilation and cache-loading, before the maximum work rate applies to the node.

Ramp-up configuration units

SystemInput rate limiter

The ramp-up configuration of the SystemInput rate limiter is expressed in terms of a raw number of SLEE events. That is, the startRate and rateIncrement specify an exact number of events.

For example, if the startRate is 50 then ramp-up begins with an allowance of 50 events per time unit.

The rateIncrement is added to the allowed rate every time Rhino processes eventsPerIncrement events with no rejected events. Rhino counts all events processed, regardless of whether or not they go through the SystemInput limiter.

Other rate limiters

The ramp-up configuration of all other rate limiters is expressed in terms of a percentage of the maximum rate of the limiter.

For example, if maxRate = 500 and startRate = 25.0 then ramp-up begins with an allowance of 500 x 25.0% = 125 units of work per time unit.

Following on with this example, if rateIncrement = 10.0 then the allowed rate increases by 500 x 10.0% = 50 units of work per time unit every time that eventsPerIncrement units of work are used in the limiter.

Enabling or disabling ramp-up

Below is a summary of what happens depending on whether ramp-up is enabled or disabled for the SystemInput rate limiter.

Enabled Disabled

  • First, Rhino sets the SystemInput limiter’s maximum allowed rate to startRate.

  • Then, every time Rhino processes eventsPerIncrement events, with no rejected events, it adds rateIncrement to the rate.

  • Ramp-up finishes when the current rate reaches the maxRate value set for the SystemInput limiter.

Nothing special happens when the node starts — the maximum rate the SystemInput limiter allows is simply maxRate.

Below is a summary of what happens when ramp-up is enabled or disabled for any other rate limiter.

Enabled Disabled

  • First, Rhino sets the rate limiter’s maximum allowed rate to maxRate x startRate%.

  • Then, every time eventsPerIncrement units of work are used in the limiter, it adds maxRate x rateIncrement% to the rate.

  • Ramp-up finishes when the current rate reaches the maxRate value set for the rate limiter.

Nothing special happens when the node starts — the maximum rate the rate limiter allows is simply maxRate.
Warning Ramp-up has no effect if the rate limiter’s bypassed flag is true.
Warning Ramp-up restarts from startRate if any property of the ramp-up’s configuration is modified, if the limiter’s maxRate is changed, or if the limiter changes from being bypassed to not being bypassed.
Tip You configure ramp-up globally, but each node ramps up independently. So if a node restarts, it ramps up again — without affecting other already running nodes.
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Rhino Version 3.1