Re: [PATCH] sched: Fix adverse effects of NFS client on interactive response

[Mike Galbraith <efault@gmx.de>]

At 10:40 AM 1/8/2006 +1100, Peter Williams wrote:
> Mike Galbraith wrote:
> > >   One slight variation of your scheme would be to measure the average 
> > > length of the CPU runs that the task does (i.e. how long it runs 
> > > without voluntarily relinquishing the CPU) and not allowing them to 
> > > defer the shift to the expired array if this average run length is 
> > > greater than some specified value.  The length of this average for each 
> > > task shouldn't change with system load.  (This is more or less saying 
> > > that it's ok for a task to stay on the active array provided it's 
> > > unlikely to delay the switch between the active and expired arrays for 
> > > very long.)
> > Average burn time would indeed probably be a better metric, but that 
> > would require doing bookkeeping is the fast path.
> Most of the infrastructure is already there and the cost of doing the 
> extra bits required to get this metric would be extremely small.  The 
> hardest bit would be deciding on the "limit" to be applied when deciding 
> whether to let a supposed interactive task stay on the active array.
Yeah, I noticed run_time when I started implementing my first cut.  (which 
is of course buggy)

> By the way, it seems you have your own scheduler versions?  If so are you 
> interested in adding them to the collection in PlugSched?
No, I used to do a bunch of experimentation in fairness vs interactivity, 
but they all ended up just trading one weakness for an other.
        -Mike 

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