Re: [PATCH] sched: Fix adverse effects of NFS client on interactive response

[Peter Williams <pwil3058@bigpond.net.au>]

Trond Myklebust wrote:
> On Fri, 2005-12-23 at 21:49 +1100, Peter Williams wrote:
> 
>>No.  It is asking whether the NORMAL interruption of this interruptible 
>>sleep will be caused by a human user action such as a keystroke or mouse 
>>action.  For the NFS client the answer to that question is unequivically 
>>no.  It's not a matter of policy it's a matter of fact.
> 
> 
>         /*
>          * Tasks that have marked their sleep as noninteractive get
>          * woken up without updating their sleep average. (i.e. their
>          * sleep is handled in a priority-neutral manner, no priority
>          * boost and no penalty.)
>          */
> 
> This appears to be the only documentation for the TASK_NONINTERACTIVE
> flag,

I guess it makes to many assumptions about the reader's prior knowledge 
of the scheduler internals.  I'll try to make it clearer.

> and I see no mention of human user actions in that comment. The
> comment rather appears to states that this particular flag is designed
> to switch between two different scheduling policies.

Changes of scheduling policy only occur via calls to sched_setscheduler().

> 
> If the flag really is only about identifying sleeps that will involve
> human user actions, then surely it would be easy to set up a short set
> of guidelines in Documentation, say, that spell out exactly what the
> purpose is, and when it should be used.

Sounds reasonable.  I'll propose some changes to the scheduler 
documentation.

> That should be done _before_ one starts charging round converting every
> instance of TASK_INTERRUPTIBLE.

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

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