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

[Peter Williams <peterw@aurema.com>]

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
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