Messages in this thread | | | Subject | Re: [PATCH] sched: Increment cache_nice_tries only on periodic lb | From | Peter Zijlstra <> | Date | Sat, 11 Sep 2010 11:32:21 +0200 |
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On Fri, 2010-09-10 at 18:19 -0700, Venkatesh Pallipadi wrote: > scheduler uses cache_nice_tries as an indicator to do cache_hot and active > load balance, when normal load balance fails. Currently, this value is changed > on any failed load balance attempt. That ends up being not so nice to workloads > that enter/exit idle often, as they do more frequent new_idle balance and > that pretty soon results in cache hot tasks being pulled in. > > Making the cache_nice_tries ignore failed new_idle balance seems to make > better sense. With that only the failed load balance in periodic load balance > gets accounted and the rate of accumulation of cache_nice_tries will not > depend on idle entry/exit (short running sleep-wakeup kind of tasks). This > reduces movement of cache_hot tasks.
Seems to make sense..
I've also wondered if it would make sense to restore 0437e109e (sched: zap the migration init / cache-hot balancing code), esp because what the comment says isn't actually true anymore, we don't use the tree for load-balancing.
But even if we were, the left size of the tree isn't the cold side, nor would I guess the right side be.. tricky stuff that.
I know Gregory Haskins has played with restoring it, and I think he found some benefit from it, although he didn't pursue it, it might be worth seeing if it does for your workloads.
I've queued the patch, thanks!
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