On Sun, 23 Jul 2017 21:22:03 -0700, Rick wrote in message <[email protected]>:
> Quoting Enrico Weigelt, metux IT consult ([email protected]): > > > Some more: I'm still running 32bit userland even on 64bit machines, > > to save some memory. Especially for applications that heavily use > > pointers, it does make a notable difference. > > Yes, the fact that x86_64 (and other 64-bit) pointers each chew up 8 > bytes[1] (64 bits) wide, and thereby gobble 2x the RAM, each, > compared to IA32, can be a significant problem in code that uses > pointers a great deal, and is very vexing. This irritation's > inescapable in 64-bit-compiled code, because those pointers need to > be able to hold the address of any valid memory location the CPU can > address, whereas 32-bit pointers can reach 4GB address space (which > seemed impossibly large not so long ago).[2] > > So, yes, IA32 compilation (preferably in an otherwise x86_64 host, as > you're doing) is just the thing for being RAM-thrifty if you don't > need to access TB of RAM and the code is making heavy use of pointers. > > Wikipedia's article on 64-bit computing says: > > The main disadvantage of 64-bit architectures is that, relative to > 32-bit architectures, the same data occupies more space in memory > (due to longer pointers and possibly other types, and alignment > padding). This increases the memory requirements of a given process > and can have implications for efficient processor cache use. > Maintaining a partial 32-bit model is one way to handle this, and is > in general reasonably effective. > > So, yay for a partial IA32 model within an x86_64 environment: > smaller pointer-heavy binaries where you need them, but also software > access to up to 8TB physical RAM (and 4 exabytes = 2^64 of virtual > memory) where you don't -- best of both worlds. > > And, don't forget, year 2038 effects beckon, starting long before > 2038. > > > [1] There are three distinct data-type models for 64-bit: ILP64, > LLP64, and LP64. But all have 8-byte pointers. The differences lie > in lengths of non-pointer data types. > > [2] What really changed my mind about this is VM technology. Ability > to have the production server host in one VM and the beta in another, > and the small host OS doing security & other monitoring of both, is > cool. _______________________________________________ ..one possible fix: https://wiki.debian.org/X32Port minus systemd -- ..med vennlig hilsen = with Kind Regards from Arnt Karlsen ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. _______________________________________________ Dng mailing list [email protected] https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
