Author: James Robertson
Date: 07:59:14 10/26/98
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On October 25, 1998 at 13:28:05, Robert Hyatt wrote: [....] >> >>I still have problems understanding. Suppose you have, starting at address 0, >>four 8-bit values. If you access the first, then the whole "clump" of 32 bytes >>are loaded into the L2 cache. Ok, that makes sense. >> >>Suppose you access the second byte in chunk 0. Does the computer load chunk 0 >>(bytes 0-3) into memory? or does it load bytes 1-4 into memory? Thanks for the >>help! >> >>James >> > >cache lines are *always* aligned on 32 byte boundaries... so if you access >*any* byte between 0 and 31, all the bytes in the line get loaded from bytes >0-31 in memory... non-boundary aligned caches were done many years ago, but >cause problems with todays 32 bit "banks"... > Ok, this clears up one problem I got from not reading enough of the previous messages in this thread.... the cache is 32 bytes long, not 32 bits. Suppose you have an array, say, of 50 3-bit structures. Obviously 32 is not divisible by 3, so will the machine "split" a structure between two lines? Obviously this is necessary for huge structures, but are smaller treated differently? James
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