Need to revise my text next time. Hope it's legible. 2010/5/25 Adriano Moura <adriano.lols@xxxxxxxxx>: > This is actually normal. 64 bits systems uses 64bits per memory > address, by default. > > That alone would make 64bits systems eat twice as much memory than a > 32bit systems. Of course you can program can be coded to use 32bit > variables, but hey, isn't the larger number representation one of the > 64bits advantage? > > Also, if you want 64bit systems, you may want huge quantities of > memory. More than 3GB, which makes most of the memory consumption > somewhat useless. > > 2010/5/24 Dan McGee <dpmcgee@xxxxxxxxx>: >> On Mon, May 24, 2010 at 8:13 PM, Gary Wright <wriggary@xxxxxxxxx> wrote: >>> 2010/5/24 Frédéric Perrin <frederic.perrin@xxxxxxxx>: >>> >>>> On a 64 bit machine, in « char *p; », p will use 64 bits (8 bytes), >>>> instead of 4 bytes in a 32 bits machine [I'm talking about p, not about >>>> *p which doesn't look like it exists]. Gary Wright seems to be saying >>>> that the impact is negligible. Nicky726 seems to be saying that there >>>> is a difference of up to 80%. I am surprised by such a claim, but there >>>> seems to be anecdotes on Google of people seeing the same thing. As I >>>> don't have a 64 bits machine, I can't test for myself. >>>> -- >>>> Fred >>> >>> Well, heres something vaguely empirical. Just downloaded the two >>> latest netinstall medias and threw them on a usb stick. I ran >>> precisely four commands after logging in as root on each netinstall >>> arch: >>> >>> 1) mkdir /mnt/tmp >>> 2) mount /dev/sda3 /mnt/tmp #my home partition >>> 3) uname -a >> /mnt/tmp/gary/memcomp >>> 4) free -m >> /mnt/tmp/gary/memcomp >>> >>> results to be seen here: >>> http://aur.pastebin.com/YwTJA6cR >>> >>> short story: ~29 MB more used on x86_64... or about 30 percent. >>> >>> But when installing a whole system, many more variables come into >>> play. It might have just been my dumb luck that ram usage ended up >>> within 1-2 mb of eachother. >> >> 47 MB - 21 MB (for a difference of 26 MB) is what you want to be >> looking at and nothing else. Throw buffers and cache out the window. >> Of course, that now skews the percentage a lot higher than what you >> stated to (47 - 21) / 21 = 123%. I'm not buying those numbers though >> as you didn't capture near enough information and not all that much >> was running. >> >> More useful are probably things like pmap comparison of the same >> binaries, etc. after doing as close to identical operations. I'm not >> sure even that would help, see the following pastebin to see those >> deceiving results: http://aur.pastebin.com/GzjTZYMe >> >> -Dan >> >
