Messages in this thread | | | Date | Sat, 14 Jan 2006 16:03:26 +1100 | From | Nick Piggin <> | Subject | Re: -mm seems significanty slower than mainline on kernbench |
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Peter Williams wrote: > Martin Bligh wrote: > >> Andy Whitcroft wrote: >> >>> Andy Whitcroft wrote: >>> >>>> Peter Williams wrote: >>>> >>>> >>>> >>>>> Attached is a new patch to fix the excessive idle problem. This patch >>>>> takes a new approach to the problem as it was becoming obvious that >>>>> trying to alter the load balancing code to cope with biased load was >>>>> harder than it seemed. >>>> >>>> >>>> >>>> >>>> Ok. Tried testing different-approach-to-smp-nice-problem against the >>>> transition release 2.6.14-rc2-mm1 but it doesn't apply. Am testing >>>> against 2.6.15-mm3 right now. Will let you know. >>> >>> >>> >>> >>> Doesn't appear to help if I am analysing the graphs right. Martin? >> >> >> >> Nope. still broken. > > > Interesting. The only real difference between this and Con's original > patch is the stuff that he did in source_load() and target_load() to > nobble the bias when nr_running is 1 or less. With this new model it > should be possible to do something similar in those functions but I'll > hold off doing anything until a comparison against 2.6.15-mm3 with the > patch removed is available (as there are other scheduler changes in -mm3). >
Ideally, balancing should be completely unaffected when all tasks are of priority 0 which is what I thought yours did, and why I think the current system is not great.
I'll probably end up taking a look at it one day, if it doesn't get fixed. I think your patch is pretty close but I didn't quite look close enough to work out what's going wrong.
-- SUSE Labs, Novell Inc.
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