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(nasm.info)Section B.4.249

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B.4.249. `PREFETCHh': Prefetch Data Into Caches
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     PREFETCHNTA m8                ; 0F 18 /0        [KATMAI]
     PREFETCHT0 m8                 ; 0F 18 /1        [KATMAI]
     PREFETCHT1 m8                 ; 0F 18 /2        [KATMAI]
     PREFETCHT2 m8                 ; 0F 18 /3        [KATMAI]

   The `PREFETCHh' instructions fetch the line of data from memory that
contains the specified byte. It is placed in the cache according to
rules specified by locality hints `h':

   The hints are:

   * `T0' (temporal data) - prefetch data into all levels of the cache
     hierarchy.

   * `T1' (temporal data with respect to first level cache) - prefetch
     data into level 2 cache and higher.

   * `T2' (temporal data with respect to second level cache) - prefetch
     data into level 2 cache and higher.

   * `NTA' (non-temporal data with respect to all cache levels) -
     prefetch data into non-temporal cache structure and into a
     location close to the processor, minimizing cache pollution.

   Note that this group of instructions doesn't provide a guarantee
that the data will be in the cache when it is needed. For more details,
see the Intel IA32 Software Developer Manual, Volume 2.