Re: [PATCH][RSDL-mm 0/7] RSDL cpu scheduler for 2.6.21-rc3-mm2

[Matt Mackall]

On Tue, Mar 13, 2007 at 10:33:18AM +0100, Mike Galbraith wrote:
> On Tue, 2007-03-13 at 09:18 +0100, Ingo Molnar wrote:
> 
> > Con, we want RSDL to /improve/ interactivity. Having new scheduler 
> > interactivity logic that behaves /worse/ in the presence of CPU hogs, 
> > which CPU hogs are even reniced to +5, than the current interactivity 
> > code, is i think a non-starter. Could you try to fix this, please? Good 
> > interactivity in the presence of CPU hogs (be them default nice level or 
> > nice +5) is _the_ most important scheduler interactivity metric. 
> > Anything else is really secondary.
> 
> I just retested with the encoders at nice 0, and the x/gforce combo is
> terrible.  Funny thing though, x/gforce isn't as badly affected with a
> kernel build.  Any build is quite noticable, but even at -j8, the effect
> doen't seem to be (very brief test warning applies) as bad as with only
> the two encoders running.  That seems quite odd.

Is gforce calling sched_yield?

Can you try testing with some simpler loads, like these:

memload:
#!/usr/bin/python
a = "a" * 16 * 1024 * 1024
while 1:
    b = a[1:] + "b"
    a = b[1:] + "c"

execload:
#!/bin/sh
exec ./execload

forkload:
#!/bin/sh
./forkload&

pipeload:
#!/usr/bin/python
import os
pi, po = os.pipe()
if os.fork():
  while 1:
    os.write(po, "A" * 4096)
else:
  while 1:
    os.read(pi, 4096)

-- 
Mathematics is the supreme nostalgia of our time.
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