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It is not clear that this slowdown only occurs when iterating the array multiple times. This fixes that issue. #341

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It is not clear that this slowdown only occurs when iterating the array multiple times. This fixes that issue. #341

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10 changes: 6 additions & 4 deletions content/english/hpc/cpu-cache/associativity.md
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Expand Up @@ -6,15 +6,17 @@ weight: 11
Consider a [strided incrementing loop](../cache-lines) over an array of size $N=2^{21}$ with a fixed step size of 256:

```cpp
for (int i = 0; i < N; i += 256)
a[i]++;
for (int j = 0; j < K; j++)
for (int i = 0; i < N; i += 256)
a[i]++;
```

And then this one, with the step size of 257:

```cpp
for (int i = 0; i < N; i += 257)
a[i]++;
for (int j = 0; j < K; j++)
for (int i = 0; i < N; i += 257)
a[i]++;
```

Which one will be faster to finish? There are several considerations that come to mind:
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