3 ms·

Noob question, aren't the trillions of cycle including 'refreshing' read/write that wouldn't be necessary with persistent memory ?

• adrian_b 3y ago
  You can trivially exceed one million write cycles in only a second with a modern CPU, just by incrementing a shared counter (which cannot be cached).
  • adwn 3y ago
    > just by incrementing a shared counter (which cannot be cached) That's not true, a shared counter (i.e., an atomic integer) is cached – in fact, there's no guarantee that its value is ever written back to system RAM. You're probably thinking of non-cacheable memory: the kernel can set the MMU attributes of a memory page such that the CPU will avoid the cache when it accesses addresses in that page. This is completely independent of atomic accesses on memory locations [1]. [1] At least typically – there may well be CPUs which disallow atomic accesses on non-cacheable memory.
    • SonOfLilit 3y ago
      I assume by "which cannot be cached" he meant "which is in a page configured as non-cacheable in the MMU", i.e. exactly what you said
      • adwn 3y ago
        But then why would it have to be a shared counter? Any write to a non-cacheable memory location is transmitted to system RAM, it doesn't have to be shared with other cores, nor does it have to be a counter.
        • tuatoru 3y ago
          Because it is used by a peripheral.