[MDEV-7959] Item::cmp_type() takes 0.15% in OLTP RO - JIRA

Details

Type: Bug
Status: Open
Priority: Minor
Resolution: Unresolved
Affects Version/s: 10.1
Fix Version/s: 10.1
Component/s: None
Labels:
None

Epic Link:
Performance: micro optimizations

Description

Data comes from Sandy Bridge system running sysbench OLTP RO in 1 thread against 1 table.

Call graphs:

-   0.15%  mysqld  mysqld
   - Item::cmp_type() const
      + 37.20% Item_func::fix_fields(THD*, Item**)
      + 13.65% Item_func::setup_args_and_comparator(THD*, Arg_comparator*)
      + 10.08% Item_equal::add_const(Item*, Item*)
      + 5.16% Item_equal::fix_fields(THD*, Item**)
      + 4.68% build_equal_items_for_cond(THD*, Item*, COND_EQUAL*, bool)
      + 4.36% update_ref_and_keys(THD*, st_dynamic_array*, st_join_table*, unsigned int, Item*, unsigned long long, st_select_lex*, st_sargable_param**) [clone .isra.253]
      + 4.14% get_mm_parts(RANGE_OPT_PARAM*, Item*, Field*, Item_func::Functype, Item*, Item_result) [clone .isra.162] [clone .part.163]
      + 3.54% Item_func_between::fix_length_and_dec()
      + 2.94% check_simple_equality(Item*, Item*, Item*, COND_EQUAL*)
      + 2.69% Item::cache_const_expr_transformer(unsigned char*)
      + 2.13% Item_bool_func2::set_cmp_func()
      + 1.94% Arg_comparator::set_cmp_func(Item_result_field*, Item**, Item**, bool)
      + 1.63% Field::can_optimize_keypart_ref(Item_func const*, Item const*) const
      + 1.27% Item::charset_for_protocol() const
      + 1.11% Item_equal::fix_length_and_dec()
      + 0.95% Item::init_make_field(Send_field*, enum_field_types)
      + 0.80% Protocol::send_result_set_metadata(List<Item>*, unsigned int)
      + 0.79% Item_equal::Item_equal(Item*, Item*, bool)
      + 0.63% get_mm_leaf(RANGE_OPT_PARAM*, Item*, Field*, st_key_part*, Item_func::Functype, Item*)

This is virtual method which can't be inlined. Most time spent for function call convention. Check if we can revoke it's virtual status.

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Alexander Barkov added a comment - 2015-05-25 12:46 - edited

In this script:

DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (
  id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
   k INTEGER UNSIGNED DEFAULT '0' NOT NULL,
   c CHAR(120) DEFAULT '' NOT NULL,
   pad CHAR(60) DEFAULT '' NOT NULL,
   PRIMARY KEY (id)
) ENGINE=MyISAM;
INSERT INTO t1 (k, c, pad) VALUES (10, 'a', 'xxx');
INSERT INTO t1 (k, c, pad) VALUES (11, 'a', 'xxx');
INSERT INTO t1 (k, c, pad) VALUES (12, 'a', 'xxx');
INSERT INTO t1 (k, c, pad) VALUES (13, 'a', 'xxx');
INSERT INTO t1 (k, c, pad) VALUES (14, 'a', 'xxx');
INSERT INTO t1 (k, c, pad) VALUES (15, 'a', 'xxx');
INSERT INTO t1 (k, c, pad) VALUES (16, 'a', 'xxx');
SELECT * FROM t1 WHERE id=13;

the last SELECT query generates the following Item::cmp_type() calls (7 calls total):

#1  0x0000555555c788a8 in Item_func::setup_args_and_comparator (
#2  0x0000555555c78a9b in Item_bool_func2::fix_length_and_dec (
#3  0x0000555555ca5e38 in Item_func::fix_fields (this=0x7fff500014a8, 
...
#1  0x0000555555a911dd in Arg_comparator::set_cmp_func (this=0x7fff50001570, 
#2  0x0000555555c78a23 in Item_func::setup_args_and_comparator (
#3  0x0000555555c78a9b in Item_bool_func2::fix_length_and_dec (
#4  0x0000555555ca5e38 in Item_func::fix_fields (this=0x7fff500014a8, 
...
#1  0x0000555555a911fc in Arg_comparator::set_cmp_func (this=0x7fff50001570, 
#2  0x0000555555c78a23 in Item_func::setup_args_and_comparator (
#3  0x0000555555c78a9b in Item_bool_func2::fix_length_and_dec (
#4  0x0000555555ca5e38 in Item_func::fix_fields (this=0x7fff500014a8, 
...
#1  0x0000555555a6ef54 in check_simple_equality (thd=0x55555a932650, 
#2  0x0000555555a6f495 in Item_func_eq::check_equality (this=0x7fff500014a8, 
#3  0x0000555555a6fa77 in Item_func_eq::build_equal_items (
#4  0x0000555555a700e3 in build_equal_items (join=0x7fff50001708, 
#5  0x0000555555a737af in optimize_cond (join=0x7fff50001708, 
...
#1  0x0000555555c89292 in Item_equal::Item_equal (this=0x7fff50002228, 
#2  0x0000555555a6f18e in check_simple_equality (thd=0x55555a932650, 
#3  0x0000555555a6f495 in Item_func_eq::check_equality (this=0x7fff500014a8, 
#4  0x0000555555a6fa77 in Item_func_eq::build_equal_items (
#5  0x0000555555a700e3 in build_equal_items (join=0x7fff50001708, 
#6  0x0000555555a737af in optimize_cond (join=0x7fff50001708, 
...
#1  0x0000555555c8a114 in Item_equal::fix_length_and_dec (this=0x7fff50002228)
#2  0x0000555555c89d79 in Item_equal::fix_fields (this=0x7fff50002228, 
#3  0x0000555555a6fb38 in Item_func_eq::build_equal_items (
#4  0x0000555555a700e3 in build_equal_items (join=0x7fff50001708, 
#5  0x0000555555a737af in optimize_cond (join=0x7fff50001708, 
...
#1  0x0000555555c15e98 in Field::can_optimize_keypart_ref (
#2  0x0000555555a5c649 in add_key_part (keyuse_array=0x7fff50001a10, 
#3  0x0000555555a5d6bb in update_ref_and_keys (thd=0x55555a932650, 
#4  0x0000555555a585e6 in make_join_statistics (join=0x7fff50001708, 
#5  0x0000555555a505fc in JOIN::optimize_inner (this=0x7fff50001708)
#6  0x0000555555a4f590 in JOIN::optimize (this=0x7fff50001708)

5 out of 7 calls are done by Item_field
2 out of 7 calls are done by Item_int

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Alexander Barkov added a comment - 2015-05-25 12:46 - edited In this script: DROP TABLE IF EXISTS t1; CREATE TABLE t1 ( id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT, k INTEGER UNSIGNED DEFAULT '0' NOT NULL, c CHAR(120) DEFAULT '' NOT NULL, pad CHAR(60) DEFAULT '' NOT NULL, PRIMARY KEY (id) ) ENGINE=MyISAM; INSERT INTO t1 (k, c, pad) VALUES (10, 'a', 'xxx'); INSERT INTO t1 (k, c, pad) VALUES (11, 'a', 'xxx'); INSERT INTO t1 (k, c, pad) VALUES (12, 'a', 'xxx'); INSERT INTO t1 (k, c, pad) VALUES (13, 'a', 'xxx'); INSERT INTO t1 (k, c, pad) VALUES (14, 'a', 'xxx'); INSERT INTO t1 (k, c, pad) VALUES (15, 'a', 'xxx'); INSERT INTO t1 (k, c, pad) VALUES (16, 'a', 'xxx'); SELECT * FROM t1 WHERE id=13; the last SELECT query generates the following Item::cmp_type() calls (7 calls total): #1 0x0000555555c788a8 in Item_func::setup_args_and_comparator ( #2 0x0000555555c78a9b in Item_bool_func2::fix_length_and_dec ( #3 0x0000555555ca5e38 in Item_func::fix_fields (this=0x7fff500014a8, ... #1 0x0000555555a911dd in Arg_comparator::set_cmp_func (this=0x7fff50001570, #2 0x0000555555c78a23 in Item_func::setup_args_and_comparator ( #3 0x0000555555c78a9b in Item_bool_func2::fix_length_and_dec ( #4 0x0000555555ca5e38 in Item_func::fix_fields (this=0x7fff500014a8, ... #1 0x0000555555a911fc in Arg_comparator::set_cmp_func (this=0x7fff50001570, #2 0x0000555555c78a23 in Item_func::setup_args_and_comparator ( #3 0x0000555555c78a9b in Item_bool_func2::fix_length_and_dec ( #4 0x0000555555ca5e38 in Item_func::fix_fields (this=0x7fff500014a8, ... #1 0x0000555555a6ef54 in check_simple_equality (thd=0x55555a932650, #2 0x0000555555a6f495 in Item_func_eq::check_equality (this=0x7fff500014a8, #3 0x0000555555a6fa77 in Item_func_eq::build_equal_items ( #4 0x0000555555a700e3 in build_equal_items (join=0x7fff50001708, #5 0x0000555555a737af in optimize_cond (join=0x7fff50001708, ... #1 0x0000555555c89292 in Item_equal::Item_equal (this=0x7fff50002228, #2 0x0000555555a6f18e in check_simple_equality (thd=0x55555a932650, #3 0x0000555555a6f495 in Item_func_eq::check_equality (this=0x7fff500014a8, #4 0x0000555555a6fa77 in Item_func_eq::build_equal_items ( #5 0x0000555555a700e3 in build_equal_items (join=0x7fff50001708, #6 0x0000555555a737af in optimize_cond (join=0x7fff50001708, ... #1 0x0000555555c8a114 in Item_equal::fix_length_and_dec (this=0x7fff50002228) #2 0x0000555555c89d79 in Item_equal::fix_fields (this=0x7fff50002228, #3 0x0000555555a6fb38 in Item_func_eq::build_equal_items ( #4 0x0000555555a700e3 in build_equal_items (join=0x7fff50001708, #5 0x0000555555a737af in optimize_cond (join=0x7fff50001708, ... #1 0x0000555555c15e98 in Field::can_optimize_keypart_ref ( #2 0x0000555555a5c649 in add_key_part (keyuse_array=0x7fff50001a10, #3 0x0000555555a5d6bb in update_ref_and_keys (thd=0x55555a932650, #4 0x0000555555a585e6 in make_join_statistics (join=0x7fff50001708, #5 0x0000555555a505fc in JOIN::optimize_inner (this=0x7fff50001708) #6 0x0000555555a4f590 in JOIN::optimize (this=0x7fff50001708) 5 out of 7 calls are done by Item_field 2 out of 7 calls are done by Item_int

Item::cmp_type() takes 0.15% in OLTP RO

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