Re: [PATCH] Staircase scheduler v7.4

Peter Williams
2004-06-28T23:21:38Z

Nick Piggin wrote:
> Felipe Alfaro Solana wrote:
>
>> I have tested 2.6.7-bk10 plus from_2.6.7_to_staircase_7.7 patch and,
>> while it's definitively better than previous versions, it still feels a
>> little jerky when moving windows in X11 wrt to -mm3. Renicing makes it a
>> little bit smoother, but not as much as -mm3 without renicing.
>>
>
> You know, if renicing X makes it smoother, then that is a good thing
> IMO. X needs large amounts of CPU and low latency in order to get
> good interactivity, which is something the scheduler shouldn't give
> to a process unless it is told to.

I agree. Although the X servers CPU usage is usually relatively low
(less than 5%) it does have periods when it can get quite high (greater
than 80%) for reasonably long periods. This makes it difficult to come
up with a set of rules for CPU allocation that makes sure the X server
gets what it needs (when it needs it) without running the risk of giving
other tasks with similar load patterns unnecessary and unintentional
preferential treatment.

However, I think that there is still a need for automatic boosts for
some tasks. For instance, programs such as xmms and other media
streamers are ones whose performance could worsen as a result of the X
server being reniced unless it is treated specially and the boost they
are given needs to be enough to put them before the X server in priority
order. But renicing X would enable a tightening of the rules that
govern the automatic dispensing of preferential treatment to tasks that
are perceived to be interactive which should be good for overall system
performance.

Peter
--
Peter Williams pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce