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

[Paul Jackson <pj@sgi.com>]

Ingo wrote:
> to clearly stress the 'might easily fail' restriction. But if userspace 
> is well-behaved on Andy's systems (which it seems to be), then in 
> practice it should be resizable. 

At first glance, this is the sticky point that jumps out at me.

Andy wrote:
>    My experience is that after some days or weeks of running have gone
>    by, there is no possible way short of a reboot to get pages merged
>    effectively back to any pristine state with the infrastructure that 
>    exists there.

I take it, from what Andy writes, and from my other experience with
similar customers, that his workload is not "well-behaved" in the
sense you hoped for.

After several diverse jobs are run, we cannot, so far as I know,
merge small pages back to big pages.

I have not played with Mel Gorman's Fragmentation Avoidance patches,
so don't know if they would provide a substantial improvement here.
They well might.

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