Associative Set Cache Underestimating Hit Rate - c++

Question

I'm attempting to implement a set associative cache that uses least recently used replacement techniques. So far, my code is underestimating the amount of cache hits, and I'm not sure why. Posted below is my function, setAssoc, which takes in an int value that denotes the associativity of the cache, and also a vector of pairs that are a series of data accesses.
The function uses two 2D arrays, one to store the cache blocks, and one to store the "age" of each block in the cache.
For this particular implementation, it's okay to not worry about tag bits or anything of that nature; simply using the address divided by the block size is enough to determine the block number, then using the block number modulo the number of sets to determine the set number is sufficient.
Any insight as to why I may not be accurately predicting the right number of cache hits is appreciated!
int setAssoc(int associativity, vector<pair<unsigned long long, int>>& memAccess){
int blockNum, setNum;
int hitRate = 0;
int numOfSets = 16384 / (associativity * 32);
int cache [numOfSets][associativity];//used to store blocks
int age [numOfSets][associativity];//used to store ages
int maxAge = 0;
int hit;//use this to signal a hit in the cache
//set up cache here
for(int i = 0; i < numOfSets; i++){
for(int j = 0; j < associativity; j++){
cache[i][j] = -1;//initialize all blocks to -1
age[i][j] = 0;//initialize all ages to 0
}//end for int j
}//end for int i
for(int i = 0; i < memAccess.size(); i++){
blockNum = int ((memAccess[i].first) / 32);
setNum = blockNum % numOfSets;
hit = 0;
for(int j = 0; j < associativity; j++){
age[setNum][j]++;//age each entry in the cache
if(cache[setNum][j] == blockNum){
hitRate++;//increment hitRate if block is in cache
age[setNum][j] = 0;//reset age of block since it was just accessed
hit = 1;
}//end if
}//end for int j
if(!hit){
for(int j = 0; j < associativity; j++){
//loop to find the least recently used block
if(age[setNum][j] > maxAge){
maxAge = j;
}//end if
}//end for int j
cache[setNum][maxAge] = blockNum;
age[setNum][maxAge] = 0;
}
}//end for int i
return hitRate;
}//end setAssoc function

Answer 1

Not sure if that's the only problem in this code, but you seem to be confusing between the ages and the way number. By assigning maxAge = j, you put an arbitrary way number in your age var (which will interfere with finding the LRU way). You then use it as a way index.
I would suggest splitting this into 2 variables:
if(!hit){
for(int j = 0; j < associativity; j++){
//loop to find the least recently used block
if(age[setNum][j] > maxAge){
maxAgeWay = j;
maxAge = age[setNum][j];
}//end if
}//end for int j
cache[setNum][maxAgeWay] = blockNum;
age[setNum][maxAgeWay] = 0;
}
(with the proper initialization and bound checking of course)