How to check innodb buffer pool size in command line
mysql -u root -p
SHOW GLOBAL VARIABLES LIKE “innodb_buffer_pool_size”;
Default 134MB in mysql 8 versions
mysql> SHOW GLOBAL VARIABLES LIKE “innodb_buffer_pool_size”;
+————————-+———–+
| Variable_name | Value |
+————————-+———–+
| innodb_buffer_pool_size | 134217728 |
+————————-+———–+
1 row in set (0.00 sec)
How set innodb buffer pool size in command line dynamically
no restart required, but after restart it wipes
recommended equal to database size or atleast 50% so it loads from memory rather than disk.
SET GLOBAL innodb_buffer_pool_size=1073741824; (1gb)
Set on mysql.cnf
sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf
below [mysqld]
innodb_buffer_pool_size = 8G
innodb_buffer_pool_size =512M
SET GLOBAL innodb_buffer_pool_size=bytes;//8G 512M 256M
innodb_buffer_pool_size adjusted to multiple of innodb_buffer_pool_chunk_size * innodb_buffer_pool_instances
innodb_buffer_pool_reads/innodb_buffer_pool_read_requests*100= 0.001
Innodb_buffer_pool_read_requests are the number of requests to read a row from the buffer pool and
Innodb_buffer_pool_reads is the number of times Innodb has to perform read data from disk >> should be low
read efficiency:
write efficiency:
Adjusting buffer pool size according usage
after you set you can measure how much buffer pool utilization by this possible way its one of other things.
buffer pool pages /free vs
(Innodb_buffer_pool_pages_total – Innodb_buffer_pool_pages_free)
—————————————————————-
Innodb_buffer_pool_pages_total
Previously ISET Buffer pool size to 1GB
i am calculating it
buffer pool Pages
SHOW GLOBAL STATUS LIKE ‘Innodb_buffer_pool_pages%’;
(Innodb_buffer_pool_pages_total – Innodb_buffer_pool_pages_free)
—————————————————————-
Innodb_buffer_pool_pages_total
Innodb_buffer_pool_pages_total | 8192 |
+———————————-+——
| Innodb_buffer_pool_pages_free | 1020
8192-1020/8192= 0.875488281 *100= 87.5%
SHOW GLOBAL STATUS LIKE ‘Innodb_buffer_pool_pages%’;
+———————————-+——-+
| Variable_name | Value |
+———————————-+——-+
| Innodb_buffer_pool_pages_data | 31484 |
| Innodb_buffer_pool_pages_dirty | 0 |
| Innodb_buffer_pool_pages_flushed | 20608 |
| Innodb_buffer_pool_pages_free | 33128 |
| Innodb_buffer_pool_pages_misc | 924 |
| Innodb_buffer_pool_pages_total | 65536 |
(65536-33128)/65536*100=49.4% (1GB i set maybe i can decrease to 512MB)
2nd time calculation
free -m
total used free shared buff/cache available
Mem: 3693 1726 208 134 1758 1560
free -m
total used free shared buff/cache available
Mem: 3693 1726 208 134 1758 1560
after reducing bp size
free -m
total used free shared buff/cache available
Mem: 3693 1200 584 135 1908 2091
total used free shared buff/cache available
Mem: 3693 1200 584 135 1908 2091
SHOW GLOBAL STATUS LIKE ‘Innodb_buffer_pool_pages%’;
+———————————-+——–+
| Variable_name | Value |
+———————————-+——–+
| Innodb_buffer_pool_pages_data | 36099 |
| Innodb_buffer_pool_pages_dirty | 0 |
| Innodb_buffer_pool_pages_flushed | 702960 |
| Innodb_buffer_pool_pages_free | 28445 |
| Innodb_buffer_pool_pages_misc | 992 |
| Innodb_buffer_pool_pages_total | 65536 |
+———————————-+——–+
+———————————-+——–+
| Variable_name | Value |
+———————————-+——–+
| Innodb_buffer_pool_pages_data | 36099 |
| Innodb_buffer_pool_pages_dirty | 0 |
| Innodb_buffer_pool_pages_flushed | 702960 |
| Innodb_buffer_pool_pages_free | 28445 |
| Innodb_buffer_pool_pages_misc | 992 |
| Innodb_buffer_pool_pages_total | 65536 |
+———————————-+——–+
Total – free /toal
(65536-28445)/65536*100=56.6 %
anyway i decreased to 512 MB
SHOW GLOBAL STATUS LIKE ‘Innodb_buffer_pool_pages%’;
+———————————-+——-+
| Variable_name | Value |
+———————————-+——-+
| Innodb_buffer_pool_pages_data | 30080 |
| Innodb_buffer_pool_pages_dirty | 0 |
| Innodb_buffer_pool_pages_flushed | 180 |
| Innodb_buffer_pool_pages_free | 1834 |
| Innodb_buffer_pool_pages_misc | 854 |
| Innodb_buffer_pool_pages_total | 32768 |
+———————————-+——-+
+———————————-+——-+
| Variable_name | Value |
+———————————-+——-+
| Innodb_buffer_pool_pages_data | 30080 |
| Innodb_buffer_pool_pages_dirty | 0 |
| Innodb_buffer_pool_pages_flushed | 180 |
| Innodb_buffer_pool_pages_free | 1834 |
| Innodb_buffer_pool_pages_misc | 854 |
| Innodb_buffer_pool_pages_total | 32768 |
+———————————-+——-+
and restarted
service mysql restart
determine the actual size of your buffer pool. For instance, this simple formula gives us the total size of buffer pool in bytes:
Innodb_buffer_pool_pages_total * innodb_page_size
The innodb_page_size can be retrieved using a SHOW VARIABLES query:
SHOW VARIABLES LIKE “innodb_page_size”
SHOW VARIABLES LIKE “innodb_page_size”;
innodb_page_size | 16384 |
16384
Innodb_buffer_pool_pages_total * innodb_page_size
65536*16384= (1073741824 bytes equal to 1GB)
innodb_log_file_size = 1G
innodb_log_buffer_size = 256M
innodb_io_capacity = 1000
buffer pool caches
innodb_read_io_threads=4
innodb_write_io_threads=8 #To stress the double write buffer
innodb_buffer_pool_size=20G
innodb_buffer_pool_load_at_startup=ON
innodb_log_file_size = 32M #Small log files, more page flush
innodb_log_files_in_group=2
innodb_file_per_table=1
innodb_log_buffer_size=8M
innodb_flush_method=O_DIRECT
innodb_flush_log_at_trx_commit=0
skip-innodb_doublewrite #commented or not depending on test
Allocating mysql memory
MySQL buffers, temporary tables, connection pools, and replication related buffers ,log file size,+ buffer pool
% of total RAM’ for OS needs
80% for dedicated mysql server
30-50% in shared server by free /available memory free -m
cat /proc/meminfo
SHOW GLOBAL VARIABLES LIKE “innodb_buffer_pool_size”;
innodb_buffer_pool_size | 134217728 // Bytes
134MB // it should be
innodb_buffer_pool_size = chunk size *instances (automatically)
pool size upto 80-0% for dedicated but for wordpress below 50% will be better (moniotor later)
mycase 3.7gb ram always 1-2gb free /cached by linux.
SET GLOBAL innodb_buffer_pool_size=1073741824;
increased to 1gb
doc
innodb_buffer_pool_size=8G
always be equal to or a multiple of innodb_buffer_pool_chunk_size * innodb_buffer_pool_instances
SHOW GLOBAL VARIABLES LIKE “innodb_buffer_pool_instances”;
instance 8
size 1gb
mycase 1 & chunksize 134MB
134*8= 1072MB (Bytes actually 1024 in decimal but took 1072 KBytes)
SHOW GLOBAL VARIABLES LIKE “innodb_buffer_pool_chunk_size”;
SIZE
: it should be 2x for chunksize ( 134MB defaults mysql 8)* instances
check innodb buffer pool usage efficiency
mysql * default config 134 Mb & 1 instances.
innodb reads from disk vs memory
| Innodb_buffer_pool_read_requests | 4355260687 |
| Innodb_buffer_pool_reads | 35780
| Innodb_buffer_pool_reads | 35780
innodb_buffer_pool_reads/innodb_buffer_pool_read_requests*100= 0.001
35780/4355260687*100=0.000821
SHOW GLOBAL STATUS LIKE ‘Innodb_buffer_pool%’;
SHOW GLOBAL STATUS LIKE ‘innodb_buffer_pool_rea%’;
for (high performance) Total_Instances:= Total_IO_Threads=(innodb_read_io_threads + innodb_write_io_threads)
mycase 8
innodb_write_io_threads=4
innodb_read_io_threads =4 // default however we can increase based on ready or write heavy to know this
but 4+4=8 (should be equal to CPU cores )
than 64 × innodb_read_io_threads pending read requests in SHOW ENGINE INNODB STATUS
mysql> SHOW GLOBAL STATUS LIKE ‘Com_select’;
+—————+——-+
| Variable_name | Value |
+—————+——-+
| Com_select | 36811 |
+—————+——-+
1 row in set (0.00 sec)
SHOW GLOBAL STATUS WHERE Variable_name IN (‘Com_insert’, ‘Com_update’, ‘Com_replace’, ‘Com_delete’);
+—————+——-+
| Variable_name | Value |
+—————+——-+
| Com_delete | 453 |
| Com_insert | 5242 |
| Com_replace | 0 |
| Com_update | 631 |
5242+453+631=6326 vs 36811
wordpress blog read requests 6 times bigger than then
innodb_write_io_threads=4
innodb_read_io_threads =8
(I may change threds to 4 to 8 4 to 2
SHOW VARIABLES LIKE ‘innodb_read_io_threads’;
SHOW Global VARIABLES LIKE ‘innodb_read_io_threads’;
SET GLOBAL innodb_read_io_threads=8;
If you have a high end I/O subsystem and you see more than 64 × innodb_read_io_threads pending read requests in SHOW ENGINE INNODB STATUS output, you might improve performance by increasing the value of innodb_read_io_threads.
SHOW GLOBAL STATUS LIKE ‘Innodb_buffer_pool%’;
ptimizing InnoDB Disk I/O
top command to disk uage in linux
innodb_log_file_size
innodb_io_capacity 200 defaults
based on SSD caluclated system io
SHOW GLOBAL STATUS
SHOW GLOBAL STATUS; |\
read request Disk vs / memory
Innodb_buffer_pool_reads vs Innodb_buffer_pool_read_requests
monitoring Buffer pool efficiency reads & pages
Innodb_buffer_pool_read_requests are the number of requests to read a row from the buffer pool and Innodb_buffer_pool_reads is the number of times Innodb has to perform read data from disk >> should be low
innodb_buffer_pool_reads/innodb_buffer_pool_read_requests*100= 0.001
Innodb_buffer_pool_read_ahead | 68743954 |
| Innodb_buffer_pool_read_ahead_evicted | 236110 |
| Innodb_buffer_pool_read_requests | 5030235492 |
| Innodb_buffer_pool_reads | 8375112
8375112/5030235492*100= 0.166495426
6916/28835148*100= 0.0239846177
innodb_buffer_pool_reads/innodb_buffer_pool_read_requests*100= 0.001
SHOW GLOBAL STATUS LIKE ‘innodb_buffer_pool_rea%’;
+—————————————+———-+
| Variable_name | Value |
+—————————————+———-+
| Innodb_buffer_pool_read_ahead_rnd | 0 |
| Innodb_buffer_pool_read_ahead | 23083 |
| Innodb_buffer_pool_read_ahead_evicted | 0 |
| Innodb_buffer_pool_read_requests | 47049712 |
| Innodb_buffer_pool_reads | 7727 |
+—————————————+———-+
7727/47049712*100=0.016
|
SHOW ENGINE INNODB STATUS\G
Total large memory allocated 1099431936
Dictionary memory allocated 3427245
—BUFFER POOL 7
Buffer pool size 65536
Free buffers 33763
Database pages 30856
Old database pages 11546
Buffer pool hit rate 1000 / 1000
young 5/8 vs old pages 3/8
https://dev.mysql.com/doc/refman/5.7/en/innodb-standard-monitor.html
set global thread_cache_size = 16;
SET GLOBAL innodb_buffer_pool_size =4026531840;
InnoDB Write buffer efficiency”?
* Innodb_pages_written / Innodb_buffer_pool_write_requests — Write requests that had to hit disk — <15% is ‘good’
* Innodb_buffer_pool_wait_free / Innodb_buffer_pool_write_requests — Should not have to wait to get into the buffer pool. — <1% is ‘good’
* Innodb_buffer_pool_pages_flushed / Uptime — Writes actually going to disk
* Innodb_buffer_pool_pages_flushed / max(Questions, Queries) — Buffer pool writes per query
SHOW GLOBAL STATUS LIKE ‘innodb_buffer_pool_wri%’;
+———————————–+——–+
| Variable_name | Value |
+———————————–+——–+
| Innodb_buffer_pool_write_requests | 168685 |
SHOW GLOBAL STATUS LIKE ‘Innodb_pages_written%’;
Innodb_pages_written | 23182
23182/168685*100= 13 (<15%)
SHOW GLOBAL STATUS LIKE ‘Innodb_buffer_pool_wait_free’;
Innodb_buffer_pool_wait_free 0
SHOW GLOBAL STATUS LIKE ‘Innodb_buffer_pool_wait_free’;
0/168685= 0% (<1%)
show engine innodb status\G
Buffer pool hit rate 900 / 1000
innodb_log_file_size
default 128MB
The increase means that log flushes are less frequent