Messages in this thread | | | Date | Fri, 17 Feb 2006 14:14:44 +1100 | From | Peter Williams <> | Subject | Re: [PATCH] Fix smpnice high priority task hopping problem |
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Siddha, Suresh B wrote: > On Fri, Feb 17, 2006 at 01:30:43PM +1100, Peter Williams wrote: > >>On a normal system, would either of them be moved anyway? > > > Possible. Because when the migration thread runs it moves the current running > task out of the processor and the checks in can_migrate_task() like > "sd->nr_balance_failed > sd->cache_nice_tries" can result in cache hot task > move to the idle package.. This is a round about way and we should not depend > on this behavior..
So why does it need to be retained?
> > >>>To fix my reported problem, we need to make sure that find_busiest_group() >>>doesn't find an imbalance.. >> >>I disagree. If this causes a problem with your "optimizations" then I >>think that you need to fix the "optimizations". >> >>There's a rational argument (IMHO) that this patch should be applied >>even in the absence of the smpnice patches as it prevents >>active_load_balance() doing unnecessary work. If this isn't good for >>hypo threading then hypo threading is a special case and needs to handle >>it as such. > > > active load balance is designed only with HT optimizations in mind. And now > multi-core optimizations also use this active load balance. No one else uses > active load balance.
I can see nothing in the source code that will cause active_load_balance() to be only run on hypo threaded systems. Could you please provide some pointers to the mechanism that does this.
Peter -- Peter Williams pwil3058@bigpond.net.au
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