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SubjectRe: [RFC][PATCH] O(1) Entitlement Based Scheduler
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@aurema.com
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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