Re: [PATCH] Staircase scheduler v7.4

Nick Piggin
2004-06-29T04:44:45Z

Peter Williams wrote:
> 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.
>

Well exactly. This is what the standard scheduler tries to do, and
it does have weird starvation and priority problems that pop up.

> 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.

I agree renicing X is helpful.