Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Duplicate
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10.0.6
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None
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None
Description
As Axel mentioned in his E-mail, there is performance regression between 10.0.4 and 10.0.5:
Date: Thu, 21 Nov 2013 18:32:45 +0100
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From: Axel Schwenke <axel@askmonty.org>
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To: "maria-developers@lists.launchpad.net" <maria-developers@lists.launchpad.net>
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Subject: [Maria-developers] MariaDB-10.0-beta sysbench results
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Looking for this regression I can see clear performance drop with the following revision:
revno: 3427.1.258
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revision-id: knielsen@knielsen-hq.org-20130823120213-pbhsq4zc1h3jwa0i
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parent: knielsen@knielsen-hq.org-20130823081643-f3yhupp15yw9cpy4
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committer: knielsen@knielsen-hq.org
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branch nick: work-10.0-mdev26
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timestamp: Fri 2013-08-23 14:02:13 +0200
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message:
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MDEV-26: Global transaction ID.
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Implement @@gtid_binlog_state. This is the internal state of the binlog
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(most recent GTID logged for every domain_id and server_id). This allows
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to save the state before RESET MASTER and restore it afterwards.
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Specifically sys_vars.cc part:
static unsigned char opt_gtid_binlog_state_dummy;
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static Sys_var_gtid_binlog_state Sys_gtid_binlog_state(
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"gtid_binlog_state",
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"The internal GTID state of the binlog, used to keep track of all "
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"GTIDs ever logged to the binlog.",
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GLOBAL_VAR(opt_gtid_binlog_state_dummy), NO_CMD_LINE);
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If I comment it out, I get nice performance boost. Note that it doesn't seem to have anything to do with gtid functionality accessed by Sys_var_gtid_binlog_state methods: I removed all references to gtid code and still observe performance degradation.
It seem to be somehow caused by increase of system variables. If I add new system variable (on revision 3816), I can see performance degradation:
static ulong table_cache_instances1;
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static Sys_var_ulong Sys_table_cache_instances1(
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"table_open_cache_instances1",
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"MySQL 5.6 compatible option. Not used or needed in MariaDB",
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READ_ONLY GLOBAL_VAR(table_cache_instances1), CMD_LINE(REQUIRED_ARG),
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VALID_RANGE(1, 64), DEFAULT(1),
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BLOCK_SIZE(1), NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(NULL),
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ON_UPDATE(NULL), NULL);
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The difference is like:
64 threads, time spent: 60s, queries executed: 9326530, qps: 155442, 1 thread qps: 2428
vs
64 threads, time spent: 60s, queries executed: 9879031, qps: 164650, 1 thread qps: 2572
I was unable to reproduce performance boost with fresh 10.0 by commenting out gtid_binlog_state.
Even simpler patch for revision 3816 to see performance degradation:
=== modified file 'sql/sys_vars.cc'
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--- sql/sys_vars.cc 2013-08-14 08:48:50 +0000
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+++ sql/sys_vars.cc 2013-12-14 18:24:15 +0000
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@@ -2694,6 +2694,8 @@
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BLOCK_SIZE(1), NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(NULL),
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ON_UPDATE(NULL), NULL);
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+char buf[sizeof(Sys_table_cache_instances)];
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+
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static Sys_var_ulong Sys_thread_cache_size(
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"thread_cache_size",
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"How many threads we should keep in a cache for reuse",
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Attachments
Issue Links
- is duplicated by
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MDEV-5388 Reduce usage of LOCK_open: unused_tables
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- Closed
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