Changing p_swtime and td_slptime to ticks

[Kostik Belousov]

On Mon, Sep 17, 2007 at 05:05:57PM -0700, Jeff Roberson wrote:
> Enclosed is a patch that fixes swapping with ULE.  ULE has never properly 
> set p_swtime and td_slptime which are used by the swapout/swapin code to 
> select the appropriate thread to swap.
> 
> In 4BSD these two variables are increment once per-second as schedcpu() 
> iterates over all threads.  ULE does not have a once per-second loop 
> iterating over all threads.  So I have changed p_swtime to p_swtick and 
> td_slptime to td_slptick.  These record the value of 'ticks' when the 
> thread slept or was last swapped in or out.
> 
> For backwards compatibility I leave the values in kinfo_proc with the 
> legacy meaning by subtracting from ticks and dividing by hz.  I perform a 
> similar transformation in the swapout code to convert to seconds.  This 
> change does make it possible to use sub-second granular decisions in the 
> swap code, however I'm not sure if that's really necessary.
> 
> So that I did not disturb the 4BSD mechanism I kept the original 
> td_slptime in the td_sched area.  It should be possible to use td_slptick 
> directly but especially this close to release I did not want to change 
> 4BSD.
> 
> Feedback and testing welcome.

Purely cosmetic request: please make the ticks and hz variables in the
libkvm/kvm_proc.c static. Or, even better, move it into the struct __kvm.
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