Swappinessis aparameter that controls the relative weight given to swapping out runtime memory, as opposed to dropping pages from the system. Swappiness can be set to values between 0 and 100 inclusive. A low value causes the kernel to avoid swapping, a higher value causes the kernel to try to use swap space. The default value is60, and for most desktop systems, setting it to 100 may affect the overall performance, whereas setting it lower (even 0) may decrease response latency。

大概意思是说：Swappinesslinuxswappiness0~10060swapswappiness1000

With kernel version 3.5 and over, as well as kernel version 2.6.32-303 and over, it is likely better to use 1 for cases where 0 used to be optimal

在内核版本3.5以及以上和RHEL/CentOS kernels内核版本2.6.32-303.el6以及以上，建议使用1来代替之前内核版本下的swappiness=0的效果。

此修改在很多资料都特别提示了，如RHEL官方：

MySQLInnoDBLinuxCPUIO InnoDBcacheInnoDB

MySQLvm.swappiness=0

OSvm.swappiness = 0swapswapswap

3.5RHEL/CentOS kernels2.6.32-303vm.swappiness = 0swapnr_free + nr_filebacked < high watermarkswapswapLinuxOOMkillMySQL

wiki

解决办法

1、尽量保证Linux操作系统还有足够的内存

2、针对MySQL的服务器OS：

之vm.swappiness=0

3.5以及以上和 RHEL/CentOS kernels内核版本2.6.32-303.el6以及以上），建议设置vm.swappiness=1

3、考虑设置 /proc/(pidof -s mysqld)/oom_adj为较小的值来尽量避免MySQL由于内存不足而被关闭。

值的范围为-16~15，“-17”是一个特殊的值。如果设置为-17，就会禁止OOM Killer发出的信号（从Linux 2.6.12开始支持设置-17）。

例如：echo -15 > /proc/(pidof -s mysqld)/oom_score_adj

修改swappiness的方法

#临时修改

# Set the swappiness value as root

echo 10 > /proc/sys/vm/swappiness

# Alternatively, run this

sysctl -w vm.swappiness=10

# Verify the change

cat /proc/sys/vm/swappiness

10

# Alternatively, verify the change

sysctl vm.swappiness

vm.swappiness = 10

#永久生效需要修改配置文件sysctl.conf

/etc/sysctl.conf

vm.swappiness=10

修改mysql的oom_adj值

# cat /proc/(pidof -s mysqld)/oom_score_adj

0

# echo -15 > /proc/(pidof -s mysqld)/oom_score_adj

#当然，如果需要的话可以完全关闭 OOM killer（不推荐用在生产环境）：

# sysctl -w vm.overcommit_memory=2

# echo "vm.overcommit_memory=2" >> /etc/sysctl.conf

https://en.wikipedia.org/wiki/Swappiness#cite_note-2

https://www.percona.com/blog/2014/04/28/oom-relation-vm-swappiness0-new-kernel/

http://blog.csdn.net/longxibendi/article/details/38146521

http://www.vpsee.com/2013/10/how-to-configure-the-linux-oom-killer/