feat(rpaid):to use build-in-prefect in rapid table scan (#268)

Co-authored-by: shannon data ai <[email protected]>
Shannon-Data · Oct 15, 2024 · 3ebefc4 · 3ebefc4
1 parent f7aea57
commit 3ebefc4
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Showing 3 changed files with 18 additions and 1 deletion.
diff --git a/storage/rapid_engine/imcs/chunk.h b/storage/rapid_engine/imcs/chunk.h
@@ -147,7 +147,7 @@ class Chunk : public MemoryObject {
   // the data write to where in this chunk.
   inline uchar *where() {
     assert(m_data < m_end);
-    return m_data;
+    return m_data.load();
   }
 
   // return the real time chunk size.

diff --git a/storage/rapid_engine/imcs/data_table.cpp b/storage/rapid_engine/imcs/data_table.cpp
@@ -118,6 +118,9 @@ int DataTable::next(uchar *buf) {
   auto offset_in_chunk = m_rowid % SHANNON_ROWS_IN_CHUNK;
   ut_a(m_context->m_trx_id_cu);
   auto trx_id_ptr = m_context->m_trx_id_cu->chunk(current_chunk)->seek(offset_in_chunk);
+  // more info for __builtin_prefetch: https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
+  if ((trx_id_ptr + CACHE_LINE_SIZE) < m_context->m_trx_id_cu->chunk(current_chunk)->where())
+    __builtin_prefetch(trx_id_ptr + CACHE_LINE_SIZE, SHANNON_PREFETCH_FOR_READ, SHANNON_PREFETCH_L3_LOCALITY);
   Transaction::ID trx_id = mach_read_from_6(trx_id_ptr);
 
   for (auto idx = 0u; idx < m_field_cus.size(); idx++) {
@@ -130,6 +133,11 @@ int DataTable::next(uchar *buf) {
       return HA_ERR_GENERIC;
     });
 
+    // prefetch data for cpu to reduce the data cache miss.
+    if (cu->chunk(current_chunk)->seek(offset_in_chunk) + CACHE_LINE_SIZE < cu->chunk(current_chunk)->where())
+      __builtin_prefetch(cu->chunk(current_chunk)->seek(offset_in_chunk) + CACHE_LINE_SIZE, SHANNON_PREFETCH_FOR_READ,
+                         SHANNON_PREFETCH_L3_LOCALITY);
+
     // visibility check. if it's not visibile and does not have old version, go to next.
     if (!m_context->m_trx->is_visible(trx_id, m_context->m_table_name) &&
         !cu->chunk(current_chunk)->get_header()->m_smu) {

diff --git a/storage/rapid_engine/include/rapid_const.h b/storage/rapid_engine/include/rapid_const.h
@@ -40,6 +40,15 @@
 
 #define SHANNON_ALIGNAS alignas(CACHE_LINE_SIZE)
 
+// THE FOLLOWING FOR PREFETCH CPU INSTRUCTION.
+#define SHANNON_PREFETCH_FOR_READ 0
+#define SHANNON_PREFETCH_FOR_WRITE 1
+
+#define SHANNON_PREFETCH__NONE_LOCALITY 0
+#define SHANNON_PREFETCH_L3_LOCALITY 1
+#define SHANNON_PREFETCH_L2_LOCALITY 2
+#define SAHNNON_PREFETCH_L1_LOCALITY 3
+
 namespace ShannonBase {
 using row_id_t = size_t;
 /** Handler name for rapid */