On Jul 2, 2012, at 4:32 PM, Jens Alfke wrote: > > On Jul 2, 2012, at 4:17 PM, Kyle Sluder wrote: > >>> It depends. 64-bit values are twice as big as 32-bit ones, so they use up >>> twice as much L2 cache and RAM. >> >> I would be surprised if cache is managed at anything other than multiples of >> register width (64 bits). > > That's not the point. Data containing 64-bit values (in objects, structs, > stack frames…) is obviously bigger than data containing smaller values.
Not necessarily. The CPU could just mask off the top 32 bits when executing 32-bit opcodes on in-cache data. Each 32-bit value is still taking up 64 bits of cache space. That's probably a lot easier and more efficient than making it possible to address arbitrary 32-bit slices of cache. Note that I'm only referring to cache here, not RAM. --Kyle Sluder _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
