… SHOW INNODB STATUS mean? Mutex spin waits 5870888, rounds 19812448, OS waits 375285 To understand this text, you have to understand how InnoDB handles mutexes… SHOW INNODB STATUS. Here’s what it means. Mutex spin waits 5870888 is the number of times a thread tried to get a mutex… has ended. Don’t miss your opportunity to learn about MySQL in London from world-famous experts!
Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit
November 24, 2011 By 2 Comments
… on MySQL server. Let’s take a recent 5.1 bzr version (pre-5.1.61) and a single test, innodb_plugin.innodb… write of size 8 by thread #1 ==9090== at 0x6BC9FFF: mutex_spin_wait (sync0sync.c:441) ==9090== by 0x6B751FC: mtr_commit (sync0sync…: innobase_start_or_create_for_mysql (srv0start.c:1514) ==9090== by 0x6B48855: innobase_init(void*) (ha_innodb.cc:2284) ==9090== by 0x712F17…
Post: Scaling problems still exist in MySQL 5.5 and Percona Server 5.5
May 20, 2011 By 11 Comments
…_select,JOIN::exec,mysql_sel ect,handle_select,execute_sqlcom_select,mysql_execute_command,mysql_parse,dispatch_…array_wait_event,mutex_spin_wait,mutex_enter_func,pfs_mute x_enter_func,buf_page_get_mutex_enter,… a lot worse in this workload and innodb_adaptive_hash_index_partitions=16 available for …
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…innodb_status_fileblogpercona.commanual innodb_strict_modeblogpercona.commanual innodb_support_xablogpercona.commanual innodb_sync_spin_loopsblogpercona.commanual innodb_table_locksblogpercona.commanual innodb_thread_concurrencyblogpercona.commanual innodb…
Post: How Innodb Contention may manifest itself
July 28, 2011 By 1 Comment
… been implemented in Percona Server and MySQL 5.5, there are still workloads in which case mutex (or rw-lock) contention is… time with context switching because Innodb is not spinning too much, thus you can consider increasing innodb_sync_spin_loops to a higher number. It is worth to note fine tuning Innodb Contention with number of spin locks…
Post: kernel_mutex problem. Or double throughput with single variable
December 2, 2011 By 17 Comments
Problem with kernel_mutex in MySQL 5.1 and MySQL 5.5 is known: Bug report. In fact in MySQL 5.6 there are… kernel_mutex (and all InnoDB mutexes) has complex handling with spin loops, and there are two variables that affects mutex loops: innodb_sync_spin_loops and innodb_spin_wait… first experiment. With innodb_sync_spin_loops=100 the kernel_mutex is still the main point of contention, but InnoDB tries to prevent the…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… semaphore: Mutex at 0x2a957858b8 created file buf0buf.c line 517, lock var 0 waiters flag 0 wait is ending Mutex spin waits 5672442, rounds 3899888, OS waits 4719 RW-shared spins 5920, OS waits 2918; RW-excl spins 3463, OS… thread id 1148250464, thread declared inside InnoDB 442 mysql tables in use 1, locked 0 MySQL thread id 8079, query id 728899 localhost…
Post: The perils of InnoDB with Debian and startup scripts
January 28, 2009 By 13 Comments
… running MySQL on Debian or Ubuntu with InnoDB? You might want to disable /etc/mysql/debian-start. When you run /etc/init.d/mysql….c line 1624 Mutex spin waits 0, rounds 5023577, OS waits 24953 RW-shared spins 34364070, OS waits 33800501; RW-excl spins 5756394, OS… 1159956816 starting index read, thread declared inside InnoDB 500 mysql tables in use 7, locked 0 MySQL thread id 6424, query id 1579718…
Comment: Returning to InnoDB scalability
August 4, 2006 By 42 Comments
… innodb_thread_concurrency=4 in our my.conf . For the SHOW MUTEX STATUS output , here you go :: mysql> SHOW MUTEX STATUS ; +—————————+————-+————–+————+————-+———-+———–+—————+ | Mutex | Module | Count | Spin_waits | Spin…
Post: MySQL 5.0, 5.1 and Innodb Plugin CPU Efficiency
December 3, 2008 By 15 Comments
…it couple of weeks ago so MySQL 5.0.67, MySQL 5.1.29 and Innodb Plugin 1.0.1 were…too. You can have 2 cases when waiting on mutexes and other synchronization objects – either everything waits so …full CPU usage, or you may be waiting by spinning on the spinlock wasting CPU cycles. Detailed profiling …
