From: MenTaLguY <mental@...>
Date: 2007-03-02T06:48:51+09:00
Subject: Re: replacing the use of gettimeofday in the scheduler

On Fri, 2 Mar 2007 06:30:12 +0900, "Tomas Pospisek's Mailing Lists" <tpo2@sourcepole.ch> wrote:

> What do you mean by "defined in terms of the wall-clock"?

"wall-clock" refers to real elapsed time, rather than CPU elapsed time.  It's better to base your scheduler on CPU elapsed time, since on a heavily loaded system, a "wall-clock"-based scheduler will just thrash without getting much useful work done.

Since there aren't widespread standard APIs for CPU-time-based interrupts, most runtimes with "green thread" schedulers that are based on CPU time approximate it by counting reductions, VM instructions, or AST nodes traversed.

-mental