Re: [PATCH] Set COMMONPAGESIZE to 4KB on ppc32

[Thiemo Seufer <ica2_ts at csv dot ica dot uni-stuttgart dot de>]

Daniel Jacobowitz wrote:
[snip]
> > > > You may want to undefine it in elf[32,64}btsmip* again, because those
> > > > are the ones used by linux.
> > > 
> > > IRIX allows also larger page sizes, I don't know how it plays out there.
> > 
> > Unlike MAXPAGESIZE, COMMONPAGESIZE doesn't have to be the largest page size
> > ever allowed but the most commonly used one.  It is just an optimization.
> 
> Right - my question is whether a COMMONPAGESIZE of 4K would help or
> hurt MIPS.  I think it would help, even though the kernel now supports
> larger page sizes - because the people who care about the amount of RAM
> difference involved are likely to not have very much, and use small
> pages for efficiency.

AFAICS it saves less than one page in the data segment, and impedes
the binary loader's performance by a miniscule amount. Hmm, ELF64 MIPS
is the most likely to use large pages while having the least memory
constraints, so COMMONPAGESIZE should IMHO be defined for every MIPS
other than elf64b{,ts}mip.


Thiemo