Interesting benchmark performance (was RE: Pitiful benchmark perf ormance)

Ulf Wiger <>
Mon Jun 18 13:41:40 CEST 2001

Another option could be to allow "high-priority" ports, that are
polled e.g. just before checking the normal priority process
queue -- or just after, to reduce the starvation risk.

Not that I'm against a time- or cycle-based scheduling model.


On Mon, 18 Jun 2001, Thomas Lindgren wrote:

>Maybe the time has come to adaptively adjust the number of
>reductions before yielding (ie, rescheduling)?
>Here is a portable, straightforward approach: instead of
>compiling in a constant number of reductions, the number of
>remaining reductions should be loaded from the process
>structure when checking for yielding.
>The interesting part, then, is deciding how many reductions you
>get when you're scheduled. A simple approach is to permit the
>system to set the reductions-per-yield at runtime (per process
>or for the entire node), by using a BIF. But this must be
>supplemented by some way to measure activity, so that the
>decision can be made systematically. (Alternatively, one could
>take the approach that reductions-per-yield is set _only_
>inside the runtime, to avoid messing around with BIFs.)
>A second, orthogonal, topic to consider is how well a
>"reduction" corresponds to a time tick. A reduction can vary
>quite a bit in the amount of time it requires, because of BIFs:
>today, there are ways to bump reductions when a long-running
>BIF begins.
>Another approach to yielding might be to measure the available
>time slice in hardware cycles, rather than procedure calls. All
>desktop processors have cycle counters, for example, so it is
>viable for a wide range of systems. Unfortunately, the counters
>are often somewhat messy to work with.
>			Thomas

Ulf Wiger                                    tfn: +46  8 719 81 95
Senior System Architect                      mob: +46 70 519 81 95
Strategic Product & System Management    ATM Multiservice Networks
Data Backbone & Optical Services Division      Ericsson Telecom AB

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