Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19

Nick Piggin
2005-11-05T00:07:47Z

Andi Kleen wrote:
> On Friday 04 November 2005 22:31, Gregory Maxwell wrote:
>
>>
>>Thats the idea. The 'hugetlb zone' will only be usable for allocations
>>which are guaranteed reclaimable. Reclaimable includes userspace
>>usage (since at worst an in use userspace page can be swapped out then
>>paged back into another physical location).
>
>
> I don't like it very much. You have two choices if a workload runs
> out of the kernel allocatable pages. Either you spill into the reclaimable
> zone or you fail the allocation. The first means that the huge pages
> thing is unreliable, the second would mean that all the many problems
> of limited lowmem would be back.
>

These are essentially the same problems that the frag patches face as
well.

> None of this is very attractive.
>

Though it is simple and I expect it should actually do a really good
job for the non-kernel-intensive HPC group, and the highly tuned
database group.

Nick

--
SUSE Labs, Novell Inc.

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