It looks like sysctl shows the cache info for the little cores, at least by default: hw.cachelinesize: 128 hw.l1icachesize: 131072 hw.l1dcachesize: 65536

It looks like sysctl shows the cache info for the little cores, at least by default: hw.cachelinesize: 128 hw.l1icachesize: 131072 hw.l1dcachesize: 65536 The reported L1I and L1D matches up with the little cores. Also very interesting: if you run sysctl under Rosetta, it reports 64 bytes: % arch -x86_64 /bin/bash -c "sysctl hw.cachelinesize" hw.cachelinesize: 64 This information is exposed specifically so that app developers can optimize for the cache line size in use. I very much doubt Apple would report a false number. As for Samsung: my guess is that Apple has been using 128-byte cache lines for a long time, and Samsung simply copied that because Apple did it, without understanding the implications. That would be totally in line with what I expect from them.