The preinstalled OS is not even using 64-bit mode [LWN.net]

The preinstalled OS is not even using 64-bit mode

Posted Feb 21, 2007 18:14 UTC (Wed) by mikov (subscriber, #33179)
In reply to: The preinstalled OS is not even using 64-bit mode by k8to
Parent article: Dell users demand more Linux options (ZDNet UK)

I don't have any hard data, but see my reply to dlang above in this thread with a couple of references to SPEC2k results (which are debatable). I also remember reading about a benchmark of a 64-bit and 32-bit game on Windows where the 64-bit build was slower, so it was concluded that game developers have absolutely no incentive of testing and releasing 64-bit builds (considering WOW64). Alas, I can't find the link :-(

As far as I can tell, a typical desktop user would not see in any noticable performance difference between 32 and 64 bit, so the trouble of going to 64-bit is usually not worth it for them.

For CPU-bound stuff like codecs and compression, it sure seems that the improvement should be significant - they use little pointers, so there should be no disadvantage of 64-bits. However if you take any Java app, it has lots and lots of pointers, so it will suffer greatly. Which is ironic, because Java is supposed to be good for servers, and precisely servers are switching to 64 bit .. :-)

(Log in to post comments)

The preinstalled OS is not even using 64-bit mode

Posted Feb 21, 2007 20:11 UTC (Wed) by rafdz (guest, #41427) [Link]

i admit that using 8 bits pointers is not realistic.however 16 bits pointers i am talking about are not real pointers.they are in fact indexes that must added to a base 64 bits or 32 bits real pointers.the pointer compression methdo is explained in the following paper.
http://llvm.org/pubs/2005-06-12-MSP-PointerComp.ps.
according to that paper pointer compression is beneficial only when working set of program doesn't fit into L2 cache.on other papers it has also been proved that automatically transforming memory heap allocation into automatic pool allocation could also improbe locality and hence improve performance.it would be nice if gcc could integrate the two approaches (pointer compression and automatic pool allocation) but this obviously will require a lot of research and hard work before it will be possible.