系统调优-5(数据库服务器调优)

Tuned 工具

Tuned 默认九种工作模式，更方便快捷的提供调优设置

[root@wpic ~]# tuned-adm list
Available profiles:
- balanced                    - General non-specialized tuned profile
- desktop                     - Optimize for the desktop use-case
- latency-performance         - Optimize for deterministic performance at the cost of increased power consumption
- network-latency             - Optimize for deterministic performance at the cost of increased power consumption, focused on low latency network performance
- network-throughput          - Optimize for streaming network throughput, generally only necessary on older CPUs or 40G+ networks
- powersave                   - Optimize for low power consumption
- throughput-performance      - Broadly applicable tuning that provides excellent performance across a variety of common server workloads
- virtual-guest               - Optimize for running inside a virtual guest
- virtual-host                - Optimize for running KVM guests
Current active profile: desktop

建议设置为   latency-performance 模式

tuned-adm profile latency-performance

网络调优

单独的数据库服务器建议调整网络为最小延迟模式

内核参数

cat /proc/sys/net/ipv4/tcp_low_latency

默认值 为 0， 设置为 1 ，优化为低网络延时

客户端也需要做同样的配置

测试工具

qperf

yum install qperf -y # 安装工具包。 能查找 TCP 和 UDP 延时
qperf IP  tcp_lat  # 查 tcp 延时
qperf IP  udp_lat  # 查 udp 延时

进程间通讯

通讯分类：

• semaphores  信号
• message queues  消息队列
• shared  memory regions  共享内存区域

各种通讯内核参数：

• cd /proc/sys/kernel

semaphores ： kernel.sem
message queues: kernel.msgmnb   kernel.msgmni   kernel.msgmax
shared memory regions: kernel.shmmni  kernel.shmmall  kernel.shmmax

• 查看各个字段内核参数的设置：

[root@wpic kernel]# ipcs -l

------ Messages Limits --------
max queues system wide = 7573
max size of message (bytes) = 8192
default max size of queue (bytes) = 16384

------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 16777216
max total shared memory (kbytes) = 16777216
min seg size (bytes) = 1

------ Semaphore Limits --------
max number of arrays = 262
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767

•  查看打开的共享内存段

[root@wpic kernel]# ipcs -m -l

------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 16777216
max total shared memory (kbytes) = 16777216
min seg size (bytes) = 1

 Huge Pages

只有程序员开发的程序支持 huge page，huge page 才能被使用。如 （shmat，shmget 系统调用）

查看当前的 Huge Pages 设置

[root@wpic vm]# grep ^Huge /proc/meminfo
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB

设置 Huge Pages 内核参数

/proc/sys/vm/nr_hugepages