Re: about modularization

From: Ingo Molnar
Date: Fri Aug 03 2007 - 11:13:50 EST



* T. J. Brumfield <enderandrew@xxxxxxxxx> wrote:

> CFS is apparently better in its simplicity, however others are
> reporting that SD still provides benefits for 3D gaming. [...]

even for 3D gaming the opposite of what you say seems to be the case:

http://people.redhat.com/mingo/misc/cfs-sd-ut2004-perf.jpg
http://people.redhat.com/mingo/misc/cfs-vs-sd-wine-quake.jpg

( more such measurements were done and reported, i stopped doing
graphs after the first two. )

but in any case, the main "target" of CFS was not even SD (although it
is certainly desirable to handle any load at least as well as SD) but
the _mainline_ scheduler. SD was the primary selection of a relatively
small subset of existing Linux users, and SD had known (and intentional)
tradeoffs over the mainline scheduler in certain areas. CFS tried to do
zero tradeoffs over the existing scheduler, to not introduce regressions
to the many users who found the existing scheduler just good enough.
That's been a success so far, at the moment there's no open CFS
"interactivity regression" relative to the 2.6.22 mainline scheduler.

Ingo
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