Messages in this thread | | | Date | Fri, 20 Jan 2006 19:40:39 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [Lhms-devel] Re: [PATCH 0/5] Reducing fragmentation using zones |
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Mel Gorman wrote:> > What sort of tests would you suggest? > The tests I have been running to date are > > "kbuild + aim9" for regression testing > > "updatedb + 7 -j1 kernel compiles + highorder allocation" for seeing how > easy it was to reclaim contiguous blocks > > What tests could be run that would be representative of real-world > workloads? >
1. Using 1000+ processes(threads) at once 2. heavy network load. 3. running NFS is maybe good.
>>>> And, for people who want to remove range of memory, list-based approach >>>> will >>>> need some other hook and its flexibility is of no use. >>>> (If list-based approach goes, I or someone will do.) >>>> >>> Will do what? >>> >> add kernelcore= boot option and so on :) >> As you say, "In an ideal world, we would have both". >> > > List-based was frowned at for adding complexity to the main path so we may > not get list-based built on top of zone based even though it is certinatly > possible. One reason to do zone-based was to do a comparison between them > in terms of complexity. Hopefully, Nick Piggin (as the first big objector > to the list-based approach) will make some sort of comment on what he > thinks of zone-based in comparison to list-based. > I think there is another point.
what I concern about is Linus's word ,this: > My point is that regardless of what you _want_, defragmentation is > _useless_. It's useless simply because for big areas it is so expensive as > to be impractical.
You should make your own answer for this before posting.
From the old threads (very long!), I think one of the point was : To use hugepages, sysadmin can specifies what he wants at boot time. This guarantees 100% allocation of needed huge pages. Why memhotplug cannot specifies "how much they can remove" before booting. This will guaranntee 100% memory hotremove.
I think hugetlb and memory hotplug cannot be good reason for defragment.
Finding the reason for defragment is good. Unfortunately, I don't know the cases of memory allocation failure because of fragmentation with recent kernel.
-- Kame
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