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

Linus Torvalds
2007-04-22T23:26:45Z

On Sun, 22 Apr 2007, Juliusz Chroboczek wrote:
>
> Why not do it in the X server itself? This will avoid controversial
> policy in the kernel, and have the added advantage of working with
> X servers that don't directly access hardware.

It's wrong *wherever* you do it.

The X server should not be re-niced. It was done in the past, and it was
wrogn then (and caused problems - we had to tell people to undo it,
because some distros had started doing it by default).

If you have a single client, the X server is *not* more important than the
client, and indeed, renicing the X server causes bad patterns: just
because the client sends a request does not mean that the X server should
immediately be given the CPU as being "more important".

In other words, the things that make it important that the X server _can_
get CPU time if needed are all totally different from the X server being
"more important". The X server is more important only in the presense of
multiple clients, not on its own! Needing to renice it is a hack for a bad
scheduler, and shows that somebody doesn't understand the problem!

Linus