Re: Linux 2.4.17-pre5

From: Alan Cox (
Date: Sun Dec 09 2001 - 11:24:59 EST

> Using the scheduler i'm working on and setting a trigger load level of 2,
> as soon as the idle is scheduled it'll go to grab the task waiting on the
> other cpu and it'll make it running.

That rapidly gets you thrashing around as I suspect you've found.

I'm currently using the following rule in wake up

        if(current->mm->runnable > 0) /* One already running ? */
                cpu = current->mm->last_cpu;
                cpu = idle_cpu();
                cpu = cpu_num[fast_fl1(runnable_set)]

that is
        If we are running threads with this mm on a cpu throw them at the
                same core
        If there is an idle CPU use it
        Take the mask of currently executing priority levels, find the last
        set bit (lowest pri) being executed, and look up a cpu running at
        that priority

Then the idle stealing code will do the rest of the balancing, but at least
it converges towards each mm living on one cpu core.

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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:15 EST