Re: FSS scheduling class & ressource management

From: Vlad Grama (vgrama_at_gmail.com)
Date: 09/01/05 

Date: 1 Sep 2005 08:10:21 -0700

There are some differences, especially concerning interactive
processes. (I wouldn't call them drawbacks in your case and they
probably won't bother you, but still...).

>>From Andrei Dorofeev's blog
(http://blogs.sun.com/roller/comments/andrei/Weblog/welcome - comments
section)

<<
TS and FSS schedulers serve different purposes. WIth TS each thread is
getting the same amount of CPU cycles as any other thread. Therefore,
the more threads you own, the more CPU cycles you'll be able to get.
With FSS, all available CPU cycles are distributed between projects
(which consist of one or more threads) based on how much shares were
allocated to them. Overall, TS scheduler is better suited for running
interactive workloads that require short CPU latency as it gives
priority boost to threads that were not able to get CPU cycles because
of their low priorities. FSS doesn't do that, so it can take longer for
a thread to get on a CPU because its project owns fewer shares or it
has lots of other threads that want to run.

We can't replace TS with FSS because this would change the behavior of
applications running on the same system in different projects.
Processes in projects with larger number of threads could get fewer CPU
cycles than processes that run in projects with smaller number of
threads.
>>

Regards,
Vlad.