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

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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
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2
sql/sql_base.h
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@ -164,7 +164,7 @@ bool fill_record_n_invoke_before_triggers(THD *thd, TABLE *table,
bool insert_fields(THD *thd, Name_resolution_context *context,
const char *db_name, const char *table_name,
List_iterator<Item> *it, bool any_privileges);
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);
int setup_wild(THD *thd, TABLE_LIST *tables, List<Item> &fields,
List<Item> *sum_func_list, uint wild_num);