Re: allow non root users to set io priority "idle" ?

[varg@theor.jinr.ru (Sheplyakov Alexei)]

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On Mon, Aug 06, 2007 at 01:11:01PM +0200, Andi Kleen wrote:

> Very low priority can starve others when it holds some kernel resource
> needed by another task.  

Nevertheless ordinary users are permitted to lower priority ([re]nice)
and resource limits (setrlimit).

> For IO I suppose the same could happen too. e.g. low priority
> task wants to write out a page and keeps it locked until the IO 
> is finished. High priority task wants to access the page and has
> to wait until it is unlocked. Middle task generates an endless
> stream of IO that makes the idle priority writeout never finish.

I don't quite understand. There are a lot of other ways to starve such
high-priority process: 
1. renice the low-priority process
2. send it a signal
3. ptrace it
4. use something like cpulimit (http://cpulimit.sourceforge.net/) to stall it
....

So I think current behaviour of ionice is inconsistent (and pointless).

P.S. 
Please CC me, I'm not subscribed.

Best regards,
 Alexei

-- 
All science is either physics or stamp collecting.


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