Re: Superpages Project - sourceforge.net/projects/linuxsuperpages

[Peter Zijlstra <peterz@infradead.org>]

On Wed, 2008-10-15 at 01:51 +0000, Wildman, Tom wrote:
> A new project has been created at SourceForge with an implementation
> of the Rice University's Superpages FreeBSD prototype that has been
> ported to the 2.6 Linux kernel for IA64, x86-64, and x86-32.
> 
> The project can be found at:
> http://sourceforge.net/projects/linuxsuperpages
> 
> The major benefit of supporting Superpages is increased memory reach
> of the processor's TLB, which reduces the number of TLB misses in
> applications that have large data sets.  Some benchmarks have been
> improved 20% in execution time.
> 
> Reference www.cs.rice.edu/~jnavarro/superpages/ for more information
> about the Rice University's Superpages project.
> 
> The project is being made available to the Open Source community to
> share the implementation and knowledge.  With the enhancements to the
> x86 architectures to support multiple and large page sizes there
> should be increased interest in this functionality.

How are you proposing to address the fun issues like online compaction
etc. ?

Furthermore, what's the added advantage of dynamic superpages over
exlpicit superpage support, eg. though the use of libhugetlb?

Unless you realize online compaction and add a kind of extend allocation
to the page allocator there will hardly ever be a situation where you
can promote a page.

All of which is rather expensive to do, changing the application might
be easier and deliver better performance gains.