database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-27 18:02:13 +03:00
Code Activity

MDEV-7951 - sql_alloc() takes 0.25% in OLTP RO

Browse Source 
sql_alloc() has additional costs compared to direct mem_root allocation:
- function call: it is defined in a separate translation unit and can't be
  inlined
- it needs to call pthread_getspecific() to get THD::mem_root

It is called dozens of times implicitely at least by:
- List<>::push_back()
- List<>::push_front()
- new (for Sql_alloc derived classes)
- sql_memdup()

Replaced lots of implicit sql_alloc() calls with direct mem_root allocation,
passing through THD pointer whenever it is needed.

Number of sql_alloc() calls reduced 345 -> 41 per OLTP RO transaction.
pthread_getspecific() overhead dropped 0.76 -> 0.59
sql_alloc() overhed dropped 0.25 -> 0.06
This commit is contained in:
Sergey Vojtovich
2015-04-17 14:30:15 +04:00
parent c4d2c4e844
commit 4d1ccc4289
20 changed files with 173 additions and 157 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
sql/sql_parse.cc
View File

@ -5698,7 +5698,7 @@ static bool execute_sqlcom_select(THD *thd, TABLE_LIST *all_tables)
SELECT_LEX *param= lex->unit.global_parameters();
if (!param->explicit_limit)
param->select_limit=
new Item_int((ulonglong) thd->variables.select_limit);
new (thd->mem_root) Item_int((ulonglong) thd->variables.select_limit);
}
if (!(res= open_and_lock_tables(thd, all_tables, TRUE, 0)))
{
@ -5775,7 +5775,7 @@ static bool execute_sqlcom_select(THD *thd, TABLE_LIST *all_tables)
}
else
{
if (!result && !(result= new select_send()))
if (!result && !(result= new (thd->mem_root) select_send()))
return 1; /* purecov: inspected */
}
query_cache_store_query(thd, all_tables);
@ -7630,7 +7630,7 @@ TABLE_LIST *st_select_lex::nest_last_join(THD *thd)
void st_select_lex::add_joined_table(TABLE_LIST *table)
{
DBUG_ENTER("add_joined_table");
join_list->push_front(table);
join_list->push_front(table, parent_lex->thd->mem_root);
table->join_list= join_list;
table->embedding= embedding;
DBUG_VOID_RETURN;
@ -7808,7 +7808,7 @@ push_new_name_resolution_context(THD *thd,
left_op->first_leaf_for_name_resolution();
on_context->last_name_resolution_table=
right_op->last_leaf_for_name_resolution();
return thd->lex->push_context(on_context);
return thd->lex->push_context(on_context, thd->mem_root);
}