This should reduce/remove measurement artifacts from the shuffle vector. Since the shuffle vector is, itself, the same size as the buffer being tested for cache, it can lower the measured value by a factor of 2. In fact, it can reduce it by more than 2, because the buffer is of char and the shuffle vector is of int32 or even int64 -- meaning it could cut it by a whole order of magnitude!
Doing some concrete tests on my machine, with the new shuffle we can see a latency increase that really ramps up around 1MB (size of L2 on my laptop):
But with the old algorithm, it starts substantially earlier -- the median stabilizes to a new high value at aroung 100K, a size corresponding to nothing in particular as far as I'm aware:
This should reduce/remove measurement artifacts from the shuffle vector. Since the shuffle vector is, itself, the same size as the buffer being tested for cache, it can lower the measured value by a factor of 2. In fact, it can reduce it by more than 2, because the buffer is of char and the shuffle vector is of int32 or even int64 -- meaning it could cut it by a whole order of magnitude!
Doing some concrete tests on my machine, with the new shuffle we can see a latency increase that really ramps up around 1MB (size of L2 on my laptop):
But with the old algorithm, it starts substantially earlier -- the median stabilizes to a new high value at aroung 100K, a size corresponding to nothing in particular as far as I'm aware: