Re: [PATCH]O18.1int

Nick Piggin
2003-08-23T09:19:27Z

Thomas Schlichter wrote:

>On Saturday 23 August 2003 07:55, Con Kolivas wrote:
>
>>Some high credit tasks were being missed due to their prolonged cpu burn at
>>startup flagging them as low credit tasks.
>>
>>Low credit tasks can now recover to become high credit.
>>
>>Con
>>
>
>Hi Con!
>
>First of all... Your interactive scheduler work is GREAT! I really like it...!
>
>Now I tried to unterstand what exacly the latest patch does, and as far as I
>can see the first and the third hunk just delete respectively expand the
>macro VARYING_CREDIT(p). But the second hunk helps processes to get some
>interactive_credit until they become a HIGH_CREDIT task. This looks
>reasonable to me...
>
>So, now I wanted to know how a task may lose its interactive_credit again...
>The only code I saw doing this is exaclty the third hunk of your patch. But
>if a process is a HIGH_CREDIT task it can never lose its interactive_credit
>again. Is that intented?
>
>I think the third hunk should look like following:
>@@ -1548,7 +1545,7 @@ switch_tasks:
> prev->sleep_avg -= run_time;
> if ((long)prev->sleep_avg <= 0){
> prev->sleep_avg = 0;
>- prev->interactive_credit -= VARYING_CREDIT(prev);
>+ prev->interactive_credit -= !(LOW_CREDIT(prev));
> }
> prev->timestamp = now;
>
>As an additional idea I think interactive_credit should be allowed to be a bit
>bigger than MAX_SLEEP_AVG and a bit lower than -MAX_SLEEP_AVG. This would
>make LOW_CREDIT processes stay LOW_CREDIT even if they do some sleep and
>HIGH_CREDIT processes star HIGH_CREDIT even if they do some computing...
>
>But of course I may completely miss something...
>
>

Hi
I don't know what is preferred on lkml, but I dislike mixing booleans
and integer arithmetic.

if (!LOW_CREDIT(prev))
prev->interactive_credit--;

Easier to read IMO.