needed scheduler improvements (was: Re: SCO: "thread creation is about a thousand times faster than on native Linux")

From: Rik van Riel (riel@conectiva.com.br)
Date: Wed Aug 23 2000 - 17:05:00 EST


On Wed, 23 Aug 2000 kuznet@ms2.inr.ac.ru wrote:

> BTW look into our scheduler, which scans all the list of idle
> processes each time slice, when only one process is running
> really and the rest are deathly dead. 8)

We really should fix this, indeed.

There's also another thing which I'd like our scheduler
to do right. Suppose we have 2 processes running in the
background, calculating stuff (they'll both become low
priority, which is good).

Now one of the processes is halfway it's timeslice and
gets interrupted by something. After that short interruption
Linux continues with the _other_ cpu intensive thread,
blowing the cache and making the system slower than it should
be.

A third issue would be NUMA (and maybe some SMP) scalability.
We may want to have 'local' (per node, or per cpu) run queues
with a less opportunistic thread migration between cpus.

With memory becoming a worse and worse bottleneck, I guess we
should be a bit more careful about using the cache as best as
possible than we are now...

regards,

Rik

--
"What you're running that piece of shit Gnome?!?!"
       -- Miguel de Icaza, UKUUG 2000

http://www.conectiva.com/ http://www.surriel.com/

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