有没有办法减少 VIRT 内存使用量？我不确定使用量这么高的原因是什么。它也已经达到了 12g。
使用 top 命令
Tasks: 348 total, 1 running, 344 sleeping, 0 stopped, 3 zombie
Cpu(s): 1.4%us, 0.2%sy, 0.0%ni, 98.3%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 39131036k total, 4522864k used, 34608172k free, 228124k buffers
Swap: 16764924k total, 0k used, 16764924k free, 1316196k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
26760 www-data 20 0 312m 39m 4292 S 11 0.1 0:01.84 /usr/sbin/apache2 -
27149 www-data 20 0 312m 38m 3760 S 11 0.1 0:00.34 /usr/sbin/apache2 -
27193 www-data 20 0 312m 39m 4984 S 11 0.1 0:00.90 /usr/sbin/apache2 -
1103 mysql 20 0 9.8g 195m 8244 S 1 0.5 5:40.69 /usr/sbin/mysqld
27180 www-data 20 0 0 0 0 Z 1 0.0 0:00.47 [apache2] <defunct>
66 root 20 0 0 0 0 S 0 0.0 0:00.23 [kworker/15:0]
8037 ntp 20 0 31496 1588 1244 S 0 0.0 0:01.13 /usr/sbin/ntpd -p /
26676 www-data 20 0 332m 58m 3960 S 0 0.2 0:01.73 /usr/sbin/apache2 -
26737 www-data 20 0 290m 16m 3476 S 0 0.0 0:00.23 /usr/sbin/apache2 -
26738 www-data 20 0 312m 39m 4292 S 0 0.1 0:00.68 /usr/sbin/apache2 -
26772 www-data 20 0 289m 15m 3928 S 0 0.0 0:00.41 /usr/sbin/apache2 -
26883 www-data 20 0 312m 39m 4300 S 0 0.1 0:00.48 /usr/sbin/apache2 -
27150 www-data 20 0 284m 8372 1516 S 0 0.0 0:00.02 /usr/sbin/apache2 -
27154 www-data 20 0 312m 39m 3876 S 0 0.1 0:00.44 /usr/sbin/apache2 -
27191 www-data 20 0 329m 55m 3644 S 0 0.1 0:00.44 /usr/sbin/apache2 -
27222 webaau 20 0 17568 1636 1072 R 0 0.0 0:00.06 top
1 root 20 0 24428 2388 1352 S 0 0.0 0:03.60 /sbin/init
我的cnf
#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html
# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port = 3306
socket = /var/run/mysqld/mysqld.sock
# Here is entries for some specific programs
# The following values assume you have at least 32M ram
# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket = /var/run/mysqld/mysqld.sock
nice = 0
[mysqld]
#
# * Basic Settings
#
user = mysql
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
port = 3306
basedir = /usr
datadir = /var/lib/mysql
tmpdir = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address = 127.0.0.1
#
# * Fine Tuning
#
key_buffer = 16M
max_allowed_packet = 16M
thread_stack = 192K
thread_cache_size = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover = BACKUP
max_connections = 300
#table_cache = 64
#thread_concurrency = 10
#
# * Query Cache Configuration
#
query_cache_limit = 1M
query_cache_size = 64M
#added by SRTPL
# changed qauery_cache_size from 16M to 32
tmp_table_size = 64M
max_heap_table_size = 64M
table_cache = 500
wait_timeout = 900
interactive_timeout = 900
#2880
#End of adding
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file = /var/log/mysql/mysql.log
#general_log = 1
#
# Error logging goes to syslog due to /etc/mysql/conf.d/mysqld_safe_syslog.cnf.
#
# Here you can see queries with especially long duration
#log_slow_queries = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
# other settings you may need to change.
#server-id = 1
#log_bin = /var/log/mysql/mysql-bin.log
expire_logs_days = 10
max_binlog_size = 100M
#binlog_do_db = include_database_name
#binlog_ignore_db = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem
[mysqldump]
quick
quote-names
max_allowed_packet = 16M
[mysql]
#no-auto-rehash # faster start of mysql but no tab completition
[isamchk]
key_buffer = 16M
#
# * IMPORTANT: Additional settings that can override those from this file!
# The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/
我遇到的另一个问题是，尽管没有进程正在使用内存，但实际内存使用率很高。在 my.cnf 中调整几次并重新启动后，实际内存使用率高的情况不再发生。
使用 ubuntu 12.04
5.5.22-0ubuntu1
Apache2.2.22
PHP 版本 5.3.10-1ubuntu3.1
答案1
MySQL 仅映射了内存页面，但实际上并未使用它们。VIRT!= 内存使用。Linux 内存使用情况有时会非常令人困惑。
您可以从顶部输出中自己看到没有使用交换，并且 RAM 也基本未使用。