# MySQL memory issue **URL:** \ **Category:** Other MySQL® Questions\ **Created:** [December 22, 2012, 7:51am UTC](https://forums.percona.com/t/mysql-memory-issue/1955 "2012-12-22T07:51:43Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![rameshvs02](https://avatars.discourse-cdn.com/v4/letter/r/eada6e/32.png) [@rameshvs02](https://forums.percona.com/u/rameshvs02)\ **Post date:** [December 22, 2012, 7:51am UTC](https://forums.percona.com/t/mysql-memory-issue/1955/1 "2012-12-22T07:51:43Z")
Hi Team, One of my MySQL server process is using more memory (around 75% resident memory) from RAM. PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 7622 mysql 15 0 32.8g 27g 5510 S 10.0 76.6 55493:27 mysqld ## Server configuration 36GB RAM, 64 bit Linux OS, 16 CPU. ## MySQL configuration and status innodb\_buffer\_pool\_size = 6 GB innodb\_log\_buffer\_size=8MB join\_buffer\_size=126KB key\_buffer\_size=8MB read\_buffer\_size=126KB read\_rnd\_buffer\_size=256KB sort\_buffer\_size= 2MB Connections at a time = 500 (approx) Query per Second = 4500 (approx) Data size = 32 GB (approx) Most of the tables are in InnoDB engine and the threads are accessing InnoDB tables. When I was looking Innodb status there is lack of free pages in buffer pool. Is that the reason for using more memory from for MySQL Daemon ? If I re-size innodb\_buffer\_pool\_size to 16GB, do I get performance improvement ? * * * * * * ## Total memory allocated 6593445888; in additional pool allocated 0 Dictionary memory allocated 2092044 Buffer pool size 393215 Free buffers 1 Database pages 388677 Old database pages 143456 Modified db pages 42657 * * * Please suggest how to resolve this memory issue.. Let me know if there is any extra info required. regards ramesh ---
**Author:** ![niljoshi](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/niljoshi/32/16889_2.png) [@niljoshi](https://forums.percona.com/u/niljoshi)\ **Post date:** [December 24, 2012, 4:06am UTC](https://forums.percona.com/t/mysql-memory-issue/1955/2 "2012-12-24T04:06:47Z")
Hi Ramesh, I don’t see exactly a memory problem there. InnoDB is using all the available innodb buffer pool and that’s good. buffer pool is used for caching pages, adaptative hash, change buffer and so on. so, if you give mysql X gb of ram it will try to use it all, that variable and the innodb log file size are the two most important parameters for innodb. The usual advice for the buffer pool is to use 80% of the memory, but only if the server is dedicated. Increasing the buffer pool should increase the performance, but you might see a much larger use of memory on the top output but it should be okay. The most important thing is, it should not swap. If you are searching reason to use more memory by MySQL it can be because of other sessions variables as you have 500 connections at a time. sort\_buffer\_size= 2MB and Query per Second = 4500. imagine that only 50% of those queries needs the sort buffer. that’s 5GB more of ram needed. So if possible provide output of pt-mysql-summary utility. [http://www.percona.com/doc/percona-toolkit/2.1/pt-mysql-summ](http://www.percona.com/doc/percona-toolkit/2.1/pt-mysql-summ) ary.html. It can help us to troubleshoot this issue. ---
**Author:** ![rameshvs02](https://avatars.discourse-cdn.com/v4/letter/r/eada6e/32.png) [@rameshvs02](https://forums.percona.com/u/rameshvs02)\ **Post date:** [December 24, 2012, 5:25am UTC](https://forums.percona.com/t/mysql-memory-issue/1955/3 "2012-12-24T05:25:38Z")
Hi Nil, Thanks for the quick update on this issue. PFA pt-mysql-summary output. The maximum possible mysql memory usage in this server is 11.4G. Calculation as follows # Per-thread memory per\_thread\_buffers = read\_buffer\_size + read\_rnd\_buffer\_size + sort\_buffer\_size + thread\_stack + join\_buffer\_size max\_total\_per\_thread\_buffers = per\_thread\_buffers \* Max\_used\_connections # Server-wide memory # Global memory max\_used\_memory = server\_buffers + max\_total\_per\_thread\_buffers but in TOP mysqld RES is 27G PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 7622 mysql 15 0 32.8g 27g 5510 S 10.0 76.6 55493:27 mysqld I am bit confused, how RES (Resident memory) is showing 27g in TOP whereas mysql total used memory is 12GB (around) – regards Ramesh