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List:       linux-kernel
Subject:    Re: [Lse-tech] Re: [PATCH][RFC] Proposal For A More Scalable Scheduler
From:       Davide Libenzi <davidel () xmailserver ! org>
Date:       2001-10-31 23:53:39
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On Wed, 31 Oct 2001, Mike Kravetz wrote:

> I'm going to try and merge your 'cache warmth' replacement for
> PROC_CHANGE_PENALTY into the LSE MQ scheduler, as well as enable
> the code to prevent task stealing during IPI delivery.  This
> should still be significantly different than your design because
> MQ will still attempt to make global decisions.  Results should
> be interesting.

I'm currently evaluating different weights for that.
Right now I'm using :

    if (p->cpu_jtime > jiffies)
        weight += p->cpu_jtime - jiffies;

that might be too much.
Solutions :

1)
    if (p->cpu_jtime > jiffies)
        weight += (p->cpu_jtime - jiffies) >> 1;

2)
    int wtable[];

    if (p->cpu_jtime > jiffies)
        weight += wtable[p->cpu_jtime - jiffies];

Speed will like 1).
Other optimization is jiffies that is volatile and forces gcc to always
reload it.

static inline int goodness(struct task_struct * p, struct mm_struct
*this_mm, unsigned long jiff)

might be better, with jiffies taken out of the goodness loop.
Mike I suggest you to use the LatSched patch to 1) know how really is
performing the scheduler 2) understand if certain test gives certain
results due wierd distributions.




- Davide


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