Re: [PATCH 7/8] sched: non-zero lag renice

[Chris Friesen]

Peter Zijlstra wrote:

> Then renicing, esp when lowering nice value (getting heavier), its possible
> to get into a starvation scenario. If you got too much runtime as a very
> light task, you get shot way far too the right, which means you'll have to
> wait for a long time in order to run again.
>
> If during that wait you get reniced down, fairness would suggest you get run
> earlier, because you deserve more time.
>
> This can be solved by scaling the vruntime so that we keep the real-time
> lag invariant.

If we've already been shot way out to the right, presumably that would give us 
a large real-time lag.  If we renice to a lower nice level, wouldn't we want 
to reduce the real-time lag rather than make it constant?

Chris
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