Re: [PATCH] [request for inclusion] Realtime LSM

[Chris Wright <chrisw@osdl.org>]

* Ingo Molnar (mingo@elte.hu) wrote:
> * Chris Wright <chrisw@osdl.org> wrote:
> > I don't think they lie quite so neatly on this boundary.  There's one
> > fundamental difference which is how the dynamic priority is adjusted
> > which alters the basic preemptibility rules.
> 
> but at nice level -20 this adjustment is at most +5 priority levels -
> i.e. down to an equivalent of nice -15. Consider that a nice 0 task can
> at most get a -5 priority boost gives a nice -5 task worst-case - so the
> nice -20 task still preempts the lower prio task.

Yeah, I realize it provides some safety, I just wanted to point out
the fundamental difference.  And one point being made is that it's
the occasional worst case latencies which are the problem.  Dynamic
adjustments could be one culprit for this.

Hmm, I wonder if this could have anything to do with it.  These are
within striking range:

  PID COMMAND          NI PRI
    9 events/1        -10  34
  931 kcryptd/1       -10  33
  930 kcryptd/0       -10  34
    8 events/0        -10  34
  892 ata/1           -10  34
  891 ata/0           -10  34
 3747 udevd           -10  33
   26 kacpid          -10  31
  238 aio/1           -10  34
  237 aio/0           -10  31
  117 kblockd/1       -10  34
  116 kblockd/0       -10  34
   10 khelper         -10  34

thanks,
-chris
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