"David M. Lloyd" wrote:

>  I recently went through the trouble of figuring out how to compile Perl
>  (5.6.1) on my Ultra 5 for maximal 64-bitness, linking against the 64-bit
>  sparcv9 libraries and everything.
>  
>  My question is, has anyone done any performance comparisons against
>  regular 32-bit perl?  Is there a significant benefit to using the 64-bit
>  libraries?
>  
>  I know that in theory it would be faster, but has anyone actually bothered
>  to do it?

Actually, in theory it would be slightly slower, as all pointers become 64
bit, and that means more time to do address manipulation, and as the process
image size tends to grow as well, more page faults - again a potential
performance hit.  I haven't done any benchmarks but in general LP64
applications do take a slight performance hit.  Unless you really need more
than 2Gb of address space, stick with 32 bit.  The only LP64 apps that we
ship in Solaris are those that need to be 64 bit, mainly because they need
to fiddle with another 64-bit process - there are 35 LP64 commands under
/usr/bin, vs. 563 LP32 ones.

If you do build LP64 (and it does work OK) make sure to use the Solaris
malloc (-Dusemymalloc) as the perl one blows up over 2Gb.  With that in
place I have had perl script run and create a single 10Gb string - just to
see if it could be done :-)

Alan Burlison