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

[Peter Williams]

Timothy Miller wrote:
> 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. 

They already do e.g. renice is such a program.

> 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,

It would obviously be under root control.

> 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.

Peter
--
Dr Peter Williams, Chief Scientist                peterw@xxxxxxxxxx
Aurema Pty Limited                                Tel:+61 2 9698 2322
PO Box 305, Strawberry Hills NSW 2012, Australia  Fax:+61 2 9699 9174
79 Myrtle Street, Chippendale NSW 2008, Australia http://www.aurema.com

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