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Re: General Question on Scheduler

On Tue, Mar 05, 2002 at 02:19:37PM +0530, Anurekh Saxena wrote:
> hi,
> could you tell me the role of "last" in the switch_to macro.
> schedule() sends 'prev' as this parameter to so it could be used by 
> schedule_tail().
> I would like to know how 'prev' (i.e 'last' in switch_to) is different from 
> 'current', and how last is used in switch_to.

You're looking at

#define switch_to(prev,next,last) ...

from 2.4.

The last parameter in switch_to() is redundant and has been removed
in 2.5. It obfuscates switch_to() in 2.4. Looking at the (sole) call
of switch_to() in the 2.4 (or any other) kernel, we have:

...
        /*
         * This just switches the register state and the
         * stack.
         */
        switch_to(prev, next, prev);
        __schedule_tail(prev);

same_process:
...

This has been cleaned up in 2.5.


Cheers,
Bill
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