Re: [REPORT] cfs-v4 vs sd-0.44

William Lee Irwin III
2007-04-25T06:07:17Z

On Tue, Apr 24, 2007 at 06:22:53PM -0700, Li, Tong N wrote:
> The goal of a proportional-share scheduling algorithm is to minimize the
> above metrics. If the lag function is bounded by a constant for any
> thread in any time interval, then the algorithm is considered to be
> fair. You may notice that the second metric is actually weaker than
> first. In fact, if an algorithm achieves a constant lag bound, it must
> also achieve a constant bound for the second metric, but the reverse is
> not necessarily true. But in some settings, people have focused on the
> second metric and still consider an algorithm to be fair as long as the
> second metric is bounded by a constant.

Using these metrics it is possible to write benchmarks quantifying
fairness as a performance metric, provided weights for nice numbers.

Not so coincidentally, this also entails a test of whether nice numbers
are working as intended.

-- wli

P.S. Divide by the length of the time interval to rephrase in terms of
CPU bandwidth.