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

Martin J. Bligh
2005-11-04T01:16:55Z

> Linus writes:
>
>> Just face it - people who want memory hotplug had better know that
>> beforehand (and let's be honest - in practice it's only going to work in
>> virtualized environments or in environments where you can insert the new
>> bank of memory and copy it over and remove the old one with hw support).
>>
>> Same as hugetlb.
>>
>> Nobody sane _cares_. Nobody sane is asking for these things. Only people
>> with special needs are asking for it, and they know their needs.
>
>
> Hello, my name is Andy. I am insane. I am one of the CRAZY PEOPLE you wrote
> about.

To provide a slightly shorter version ... we had one customer running
similarly large number crunching things in Fortran. Their app ran 25%
faster with large pages (not a typo). Because they ran a variety of
jobs in batch mode, they need large pages sometimes, and small pages
at others - hence they need to dynamically resize the pool.

That's the sort of thing we were trying to fix with dynamically sized
hugepage pools. It does make a huge difference to real-world customers.

M.