database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +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_base.cc
View File

@ -7962,7 +7962,7 @@ bool setup_fields(THD *thd, Item **ref_pointer_array,
RETURN pointer on pointer to next_leaf of last element
*/
void make_leaves_list(List<TABLE_LIST> &list, TABLE_LIST *tables,
void make_leaves_list(THD *thd, List<TABLE_LIST> &list, TABLE_LIST *tables,
bool full_table_list, TABLE_LIST *boundary)
{
@ -7978,12 +7978,12 @@ void make_leaves_list(List<TABLE_LIST> &list, TABLE_LIST *tables,
tables/views were already prepared and has their leaf_tables
set properly.
*/
make_leaves_list(list, select_lex->get_table_list(),
make_leaves_list(thd, list, select_lex->get_table_list(),
full_table_list, boundary);
}
else
{
list.push_back(table);
list.push_back(table, thd->mem_root);
}
}
}
@ -8044,7 +8044,7 @@ bool setup_tables(THD *thd, Name_resolution_context *context,
leaves.empty();
if (!select_lex->is_prep_leaf_list_saved)
{
make_leaves_list(leaves, tables, full_table_list, first_select_table);
make_leaves_list(thd, leaves, tables, full_table_list, first_select_table);
select_lex->leaf_tables_exec.empty();
}
else