Re: [RFC][PATCH] O(1) Entitlement Based Scheduler

[Timothy Miller]

Peter Williams wrote:
> Timothy Miller wrote:
>  > <snip>
>
> > In fact, that may be the only "flaw" in your design.  It sounds like 
> > your scheduler does an excellent job at fairness with very low 
> > overhead.  The only problem with it is that it doesn't determine 
> > priority dynamically.
>
>
> This (i.e. automatic renicing of specified programs) is a good idea but 
> is not really a function that should be undertaken by the scheduler 
> itself.  Two possible solutions spring to mind:
>
> 1. modify the do_execve() in fs/exec.c to renice tasks when they execute 
> specified binaries

We don't want user-space programs to have control over priority.  This 
is DoS waiting to happen.

> 2. have a user space daemon poll running tasks periodically and renice 
> them if they are running specified binaries

This is much too specific.  Again, if the USER has control over this 
list, then it's potential DoS.  And if the user adds a program which 
should qualify but which is not in the list, the program will not get 
its deserved boost.

And a sysadmin is not going to want to update 200 lab computers just so 
one user can get their program to run properly.

> Both of these solutions have their advantages and disadvantages, are 
> (obviously) complicated than I've made them sound and would require a 
> great deal of care to be taken during their implementation.  However, I 
> think that they are both doable.  My personal preference would be for 
> the in kernel solution on the grounds of efficiency.

They are doable, but they are not a general solution.

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