Re: [PATCH 8/8] prepare to remove /proc/sys/vm/hugepages_treat_as_movable

From: Aneesh Kumar K.V
Date: Mon Aug 05 2013 - 21:52:12 EST

Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> writes:

>> Considering that we have architectures that won't support migrating
>> explicit hugepages with this patch series, is it ok to use
>> GFP_HIGHUSER_MOVABLE for hugepage allocation ?
> Originally this parameter was introduced to make hugepage pool on ZONE_MOVABLE.
> The benefit is that we can extend the hugepage pool more easily,
> because external fragmentation less likely happens than other zone type
> by rearranging fragmented pages with page migration/reclaim.
> So I think using ZONE_MOVABLE for hugepage allocation by default makes sense
> even on the architectures which don't support hugepage migration.

But allocating hugepages from ZONE_MOVABLE means we have pages in that
zone which we can't migrate. Doesn't that impact other features like
hotplug ?


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