Mailinglist Archive: opensuse (686 mails)

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Re: [opensuse] 64 bit vs 32 bit RAM consumption
Felix Miata wrote:
In googling the possibility of using a 64 bit kernel on an otherwise 32 bit openSUSE (consensus: don't try it), I found quite a bit of mention of 64 bit apps using twice as much RAM? Is this true? Or is it just misunderstanding arising from 64 bit using twice as many CPU registers to increase its own speed? Or something else? My main system running 32 bit 11.4 has 4GB RAM and is consistently using >50% of RAM for open apps, most of the rest for disk cache, and always around 360MB unused. Would running 64 bit on this system be consuming virtually all RAM for apps, leaving little free for disk cache?

The same claims were made when we went from 8 to 16 and 16 to 32 bit CPUs and reflect a lack of knowledge about how things work. For example, a larger instruction set means you may be able to get by with fewer instructions. It shouldn't affect data at all, as the CPUs have instructions for working with smaller than register size data.

Take a look at file sizes in 32 & 64 bit systems. You'll likely find the sizes are similar.

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