Lab Swmem Prefetch 1: Prefetch next hash

dendibakh · Dec 20, 2024 · 5d6beae · 5d6beae
1 parent 8acd3df
commit 5d6beae
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Showing 2 changed files with 15 additions and 1 deletion.
diff --git a/labs/memory_bound/swmem_prefetch_1/solution.cpp b/labs/memory_bound/swmem_prefetch_1/solution.cpp
@@ -12,7 +12,13 @@ static int getSumOfDigits(int n) {
 int solution(const hash_map_t *hash_map, const std::vector<int> &lookups) {
   int result = 0;
 
-  for (int val : lookups) {
+  for (int i = 0; i < lookups.size(); i++) {
+    int val = lookups[i];
+    if (i  < lookups.size() - 1) {
+        int future_val = lookups[i + 1];
+        int future_bucket = future_val % hash_map->getNBuckets(); 
+        __builtin_prefetch(&((hash_map->getVector())[future_bucket]));
+    }
     if (hash_map->find(val))
       result += getSumOfDigits(val);
   }

diff --git a/labs/memory_bound/swmem_prefetch_1/solution.hpp b/labs/memory_bound/swmem_prefetch_1/solution.hpp
@@ -24,6 +24,14 @@ class hash_map_t {
         int bucket = val % N_Buckets;
         return m_vector[bucket] != UNUSED;
     }
+
+    const std::vector<int>& getVector() const {
+        return m_vector;
+    }
+
+    const std::size_t& getNBuckets() const {
+        return N_Buckets;
+    }
 };
 
 void init(hash_map_t* hash_map, std::vector<int>& lookups);