Trying to understand ggc-page vs. ggc-simple

[Alexandre Oliva]

On Jan 28, 2001, msokolov@ivan.Harhan.ORG (Michael Sokolov) wrote:

> caring about page sizes and page alignment in ordinary user programs
> is completely useless and does nothing except wasting memory

Garbage collection can be done more efficiently if you can make sure
certain objects all live in the same page.  I don't recall the
details, but I recall Mark Mitchell reported immense performance gains
when ensuring that memory chunks were kept page-aligned.  You safe a
lot of page faults with that.

Laurynas Biveinis has been working on improving the memory-efficiency
of ggc-page on systems that have to use valloc().  The idea is to wrap
valloc() with some function that allocates large numbers of pages at a
time, and hands back aligned pages as requested.

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                  aoliva@{cygnus.com, redhat.com}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
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