… use this data to estimate capacity of MySQL system ? We can look at CPU and IO consumption per Query and compare it… ? You can take a look at procfs for MySQL process: root@ubuntu:/var/log/mysql# cat /proc/19018/stat 19018 (mysqld) S… you to reduce wait time and number of IOs per query as well as increase CPU time spent. This is because IO handling requires…
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
…_WAITS_HISTORY_SIZE | 10 | 5 | | PERFORMANCE_SCHEMA_EVENTS_WAITS…SOCKET | /tmp/mysql_sandbox5530.sock | /tmp/mysql_sandbox5610.sock | | …reduce overhead associated with grabbing and releasing innodb_thread_concurrency slot but will increase potential starvation of queued threads especially for IO…
Post: Can Innodb Read-Ahead reduce read performance ?
June 26, 2007 By 2 Comments
… outstanding IO requests to the disk. Lets look at SHOW INNODB STATUS: ——– FILE I/O ——– I/O thread 0 state: waiting for… we have relatively sequential IO and so read-ahead is constantly triggered which makes all thread to wait on single read-ahead… Christoffer was doing (I was adviseor in this project from MySQL AB side) – to improve how Innodb read-ahead works by…
Post: MySQL caching methods and tips
April 4, 2011 By 5 Comments
… MySQL. Popular cache methods The MySQL query cache When the query cache is enabled, MySQL… to do the computation while others wait for the result. There are also…of pages is a good way to reduce the number of round trips to …face two bottlenecks: disk IO and CPU usage. Disk IO is expensive, and even…
Post: Evaluating IO subsystem performance for MySQL Needs
March 5, 2008 By 23 Comments
…asked how one can evaluate IO subsystem (Hard drive RAID or SAN) performance for MySQL needs so I’ve decided…sets for boxes with significant amounts of memory (or reducing amount of usable memory). The system I’m …24 As you can see all 64 threads are waiting for IO. Now lest see our write test which …
Post: MySQL Users Conference - Innodb
May 9, 2007 By 6 Comments
…will have to consume more than one page thus reducing performance. This is especially the problem as you …speed is however not only reason I can’t wait for this feature to be available. Building index …are far from optimal for server grade IO subsystems. These are for MySQL 4.0 at this point but we…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
…will make sure to schedule synchronous wait in front if read-ahead IO has not been started already…. allow to reduce number of TLB cache misses. huge pages along however do not stop IO pressure and… HT: ha_innodb.cc in 5.1: static MYSQL_SYSVAR_ULONG(thread_concurrency, srv_thread_concurrency, PLUGIN…
Post: Optimizing slow web pages with mk-query-digest
April 7, 2011 By 14 Comments
… only accurate when single mysql connection is used during execution of a request. If you are seeking to reduce the load on… top 10 queries on the list indeed will most likely reduce the load and improve response time for some requests. What… 0 0 0 0 # IO r ops 0 0 0 0 0 0 0 0 # IO r wait 0 0 0 0 0…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
…working set from OS cache. Operation Systems and MySQL Itself employs various strategies to attempt to …get piled up because of reduced cache efficiency many queries may start waiting on disk at once. In…do not require disk head movement, compared to IO requests in random locations other threads are …
Post: Read/Write Splitting with PHP Webinar Questions Followup
January 23, 2013 By 4 Comments
… Even the official manual page for MySQL Proxy 0.8.2 still says: “MySQL Proxy is currently an Alpha…recording of Jay’s presentation. Percona XtraDB Cluster reduces the hazards of multi-writing by keeping all… SQL thread is caught up and the IO thread is waiting. A: Yes, the “seconds behind master” is …
