Re: [patch, 2.6.11-rc2] sched: RLIMIT_RT_CPU_RATIO feature

[Peter Williams <pwil3058@bigpond.net.au>]

Bill Huey (hui) wrote:
> On Thu, Feb 03, 2005 at 08:54:24AM +1100, Peter Williams wrote:
> 
>>As Ingo said in an earlier a post, with a little ingenuity this problem 
>>can be solved in user space.  The programs in question can be setuid 
>>root so that they can set RT scheduling policy BUT have their 
>>permissions set so that they only executable by owner and group with the 
>>group set to a group that only contains those users that have permission 
>>to run this program in RT mode.  If you wish to allow other users to run 
>>the program but not in RT mode then you would need two copies of the 
>>program: one set up as above and the other with normal permissions.
> 
> 
> Again, in my post that you snipped you didn't either read or understand
> what I was saying regarding QoS,

I guess that I thought that it was overkill for the problem under 
discussion and probably won't solve it anyway.  Giving any task special 
preferential (emphasis on the preferential) treatment should require 
authorization by a suitably privileged entity at some stage.  So the 
problem of how ordinary users manage to launch tasks that receive 
preferential treatment will remain.

> nor about the large scale issues regarding
> dual/single kernel development environments. Ultimately this stuff requires
> non-trivial support in kernel space, a softirq thread migration mechanism
> and a frame driven scheduler to back IO submission across async boundaries.
> 
> My posts where pretty clear on this topic and lot of this has origins
> coming from SGI IRIX. Yes, SGI IRIX. One of the only system man enough
> to handle this stuff.
> 
> Ancient, antiquated Unix scheduler semantics (sort and run) and lack of
> control over critical facilities like softirq processing are obstacles
> to getting at this.

Sorry for upsetting you,
Peter
-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce