On 04/12/2010 05:24 PM, Christoph Lameter wrote:
To me what is relevant is that everyone in the VM camp seems to want
transparent hugepages in some shape or form, because of the about
linear speedup they provide to everything running on them on bare
metal (and an more than linear cumulative speedup in case of nested
pagetables for obvious reasons), no matter what design that it is.
We want huge pages yes. But transparent? If you can define transparent
then we may agree at some point. Certainly not transparent in the sense of
volatile objects that suddenly convert from 2M to 4K sizes causing
breakage.
Suddenly converting from 2M to 4k is a requirement, otherwise we could
just use hugetlbfs.
It's simple, we want huge pages when we have the memory and small pages
when we don't. Only the kernel knows about memory pressure, so it's up
to the kernel to break apart and put together those huge pages.
If you have other requirements, they have to come on top, not replace
our requirements.
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I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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