diff --git a/tests/cacheoptest/llc/src/huancunop.c b/tests/cacheoptest/llc/src/huancunop.c
index 1a2c9f22897a332b063adc2543c20bdd4c2819ff..1216f9b4260075e9cb32d67a54759b559eb3c44c 100644
--- a/tests/cacheoptest/llc/src/huancunop.c
+++ b/tests/cacheoptest/llc/src/huancunop.c
@@ -97,6 +97,7 @@ void test3() {
   }
 }
 
+// Flush a cacheline (512 bit) to memory
 void flush_to_memory(uint64_t paddr) {
   // printf("l3 size is set to %d KB, nr_way is set to %d, nr_bank is set to %d, ", L3_SIZE_KB, L3_NR_WAY, L3_NR_BANK);
   unsigned int set_size = L3_SIZE_KB * 1024 / L3_NR_BANK / L3_NR_WAY / 64;
@@ -117,6 +118,31 @@ void flush_to_memory(uint64_t paddr) {
   wait(100);
 }
 
+// Flush an n*512 bit address region to memory
+void flush_region_to_memory(uint64_t start_paddr, uint64_t size_in_bit) {
+  // pre-calcuated const
+  unsigned int set_size = L3_SIZE_KB * 1024 / L3_NR_BANK / L3_NR_WAY / 64;
+  unsigned int set_len = log2(set_size);
+  // printf("l3 size is set to %d KB, nr_way is set to %d, nr_bank is set to %d, ", L3_SIZE_KB, L3_NR_WAY, L3_NR_BANK);
+  // printf("nr_set is %u, set_len is %u\n", set_size, set_len);
+
+  // flush sq and sbuffer
+  asm("fence\n");
+
+  // send l3 cache flush op to l3 cache controller
+  for(uint64_t current_paddr = start_paddr; current_paddr < (start_paddr + size_in_bit); current_paddr += 512){
+    uint64_t tag = (current_paddr >> OFFSET_LEN) >> set_len; // paddr to l3 tag
+    uint64_t set = (current_paddr >> OFFSET_LEN) & (set_size-1); // paddr to l3 set
+    *(uint64_t*)(CACHE_CTRL_BASE + CTRL_TAG_OFFSET) = tag;
+    *(uint64_t*)(CACHE_CTRL_BASE + CTRL_SET_OFFSET) = set;
+    // printf("flush to memory: addr 0x%llx tag 0x%llx set 0x%llx\n", &test_buffer, tag, set);
+    (*(uint64_t*)CACHE_CMD_BASE) = CMD_CMO_CLEAN; // or CMD_CMO_FLUSH
+  }
+
+  // wait for the last cache op to finish
+  wait(100);
+}
+
 int main() {
   printf("HuanCun op (mmio based) test. Note that --no-diff is required!\n");
   printf("HuanCun l3 size is set to %d KB, nr_way is set to %d, nr_bank is set to %d, ", L3_SIZE_KB, L3_NR_WAY, L3_NR_BANK);