fragmentation calculation fix

Author: Xarbirus

llama.cpp

@@ -8898,7 +8898,7 @@ static int llama_decode_internal(
 
     // decide if we need to defrag the kv cache
     if (cparams.defrag_thold >= 0.0f) {
-        const float fragmentation = kv_self.n >= 128 ? 1.0f - float(kv_self.used + n_tokens)/float(kv_self.n) : 0.0f;
+        const float fragmentation = kv_self.n >= 128 ? 1.0f - float(kv_self.used)/float(kv_self.n) : 0.0f;
 
         // queue defragmentation for next llama_kv_cache_update
         if (fragmentation > cparams.defrag_thold) {