> Can anyone tell me, is it possible to collect number of fetches and
> cache misses for a particular array using Callgrind/Cachegrind?
> For example, I have such fragment:
>
> for (j = 0; j < length; j++) {
> for (i = ip[j]; i <= ip[j+1]-1; i++) {
> b[ia[i]] = b[ia[i]] + a[i]*x[j];
> }
> }
>
> And I want to collect information only about array /b/. How can this be
> done?
Short answer is, like this
for (j = 0; j < length; j++) {
for (i = ip[j]; i <= ip[j+1]-1; i++) {
long ia_i = ia[i];
double tmp = a[i] * x[j]; // or whatever type it is
b[ia_i] += tmp;
}
}
Now the stats for the line b[ia_i] += tmp should show you info only
for the /b/ access.
Long answer is, the question is kind-of meaningless. Cache misses are
a function of the overall memory behaviour of your program. So the
misses on b[] also depend on how the program accesses a[], x[], ip[],
etc, and you can't really measure each in isolation.
J
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