On Fri, 18 Dec 1998, MOLNAR Ingo wrote:
> On Fri, 18 Dec 1998, Rik van Riel wrote:
>
> > The real fix for this one is to try rescheduling the previous
> > processor of the task in question instead of blindly trying
> > current.
> >
> > All it takes is one pointer per processor, so it can be done
> > (very) cheaply.
>
> it's _not_ that cheap since it means a cross-CPU message pass.
That should be cheaper than an 'inapropriate' context switch
or a truckload of cache misses/invalidates.
> I'd suggest that unless you can demonstrate serious problems with
> the current code, leave this until 2.3.
I will code the thing this weekend -- if it doesn't give
a huge improvement I'll leave it in the scheduler bigpatch.
OTOH, there probably are some things that should be lifted
out of my scheduler bigpatch and put into the mainstream
kernel -- could you and Alan look into this?
> I have some code that does the mentioned SMP thing more
> apropriately (scheduling done completely at add_to_runqueue()
> time), and it's already in there partly (see reschedule_idle()),
> but it's original form was too intrusive for 2.2.
I've read the code -- it's not effective since it only looks
for idle processes. We want something better and I have a
good idea how it could look...
cheers,
Rik -- the flu hits, the flu hits, the flu hits -- MORE
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