# Understand Percona Memory Usage **URL:** \ **Category:** MySQL & MariaDB\ **Tags:** percona\ **Created:** [October 25, 2023, 11:29am UTC](https://forums.percona.com/t/understand-percona-memory-usage/26155 "2023-10-25T11:29:29Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Percona\_new](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/percona_new/32/9299_2.png) [@Percona\_new](https://forums.percona.com/u/Percona_new)\ **Post date:** [October 25, 2023, 11:29am UTC](https://forums.percona.com/t/understand-percona-memory-usage/26155/1 "2023-10-25T11:29:30Z")
Hello team, I understand that this question may have been asked before, but I’m currently in search of a method to better analyze MySQL’s memory usage. While we do have some insights into configuration and usage at the database level, there seems to be a disconnect when we examine the OS perspective. Unfortunately, I haven’t been successful in pinpointing the specific database processes that are contributing significantly to this disparity. As you will see in the example below, mysql it is configured to use ~135G of memory, yet its actual consumption exceeds 220 gigabytes. I know that this is NOT an unexpected behavior, but there is a critical need to ascertain the root cause of this variance and what it is consuming the resident memory. Thanks in advance and feel free to request any additional information. — At Database level Server version: 8.0.27-18 Percona Server (GPL), Release 18, Revision 24801e21b45 [(none)]\> select event\_name,current\_alloc from sys.memory\_global\_by\_current\_bytes limit 10; ±----------------------------------------------------------------±--------------+ | event\_name | current\_alloc | ±----------------------------------------------------------------±--------------+ | memory/innodb/buf\_buf\_pool | 114.35 GiB | | memory/sql/TABLE | 5.59 GiB | | memory/innodb/hash0hash | 3.59 GiB | | memory/performance\_schema/table\_handles | 3.44 GiB | | memory/innodb/memory | 3.10 GiB | | memory/innodb/ha\_innodb | 568.27 MiB | | memory/sql/TABLE\_SHARE::mem\_root | 476.63 MiB | | memory/performance\_schema/table\_io\_waits\_summary\_by\_index\_usage | 137.50 MiB | | memory/innodb/row0sel | 93.71 MiB | | memory/performance\_schema/table\_shares | 84.00 MiB | ±----------------------------------------------------------------±--------------+ 10 rows in set (0.00 sec) [(none)]\> select format\_bytes(sum(current\_alloc)) from sys.x$memory\_global\_by\_current\_bytes; ±---------------------------------+ | format\_bytes(sum(current\_alloc)) | ±---------------------------------+ | 132.09 GiB | ±---------------------------------+ 1 row in set (0.01 sec) – At OS level pt-summary: # Memory ``` Total | 255.7G Free | 2.0G Used | physical = 226.5G, swap allocated = 0.0, swap used = 0.0, virtual = 226.5G Shared | 3.8M Buffers | 27.2G Caches | 27.0G Dirty | 1100 kB UsedRSS | 225.3G ``` Swappiness | 10 DirtyPolicy | 20, 10 DirtyStatus | 0, 0 # Top Processes ``` PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND ``` 2047259 mysql 20 0 228.7g 222.5g 15656 S 300.0 87.0 187507:28 mysqld 801568 nicolas+ 20 0 16808 4388 3428 R 5.9 0.0 0:00.02 top 2047180 root 20 0 904328 122208 7412 S 5.9 0.0 6362:15 cadvisor 2049082 mataque+ 20 0 50712 38640 10668 S 5.9 0.0 57:46.52 mataque+ 3975914 prometh+ 20 0 1214972 172456 9624 S 5.9 0.1 6657:38 prometh+ 1 root 20 0 177388 19768 8504 S 0.0 0.0 3021:58 systemd 2 root 20 0 0 0 0 S 0.0 0.0 0:56.92 kthreadd 3 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 rcu\_gp 4 root 0 -20 0 0 0 I 0.0 0.0 0:00.22 rcu\_par+ $ free -h total used free shared buff/cache available Mem: 255Gi 226Gi 1.9Gi 3.0Mi 27Gi 26Gi Swap: 0B 0B 0B ---
**Author:** ![Percona\_new](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/percona_new/32/9299_2.png) [@Percona\_new](https://forums.percona.com/u/Percona_new)\ **Post date:** [October 31, 2023, 11:31am UTC](https://forums.percona.com/t/understand-percona-memory-usage/26155/2 "2023-10-31T11:31:51Z")
Hello team! Can anyone check on this please? Thanks! ---
**Author:** ![yunus.uyanik](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/yunus.uyanik/32/19250_2.png) [@yunus.uyanik](https://forums.percona.com/u/yunus.uyanik)\ **Post date:** [November 2, 2023, 5:22am UTC](https://forums.percona.com/t/understand-percona-memory-usage/26155/3 "2023-11-02T05:22:45Z")
Hello, You might also check by enabling performance\_schema memory instrument. And if you don’t use any memory allocator like jemalloc, the default memory allocator can show bad performance and might not release the memory. ---
**Author:** ![Percona\_new](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/percona_new/32/9299_2.png) [@Percona\_new](https://forums.percona.com/u/Percona_new)\ **Post date:** [November 10, 2023, 2:12pm UTC](https://forums.percona.com/t/understand-percona-memory-usage/26155/4 "2023-11-10T14:12:28Z")
Thanks Yunus, Thanks for your response! I already checked performance\_schema information but it does not have the information that we are looking for. We need to understand how much memory is consuming each database session in order to diagnose high memory usage. We are going to load jeamlloc to check the behavior. Thanks!