智能盒子内核参数调优

盒子测试环境：192.168.44.59
对于SSD也可以采用同样的系统策略进行测试！

内核版本：
Linux nvidia-desktop 4.9.201-tegra #1 SMP PREEMPT Fri Feb 19 08:42:04 PST 2021 aarch64 aarch64 aarch64 GNU/Linux
系统：
Ubuntu 18.04.5 LTS

内核调优参数：
#sudo cat >> /etc/sysctl.conf <<- EOF
vm.min_free_kbytes = 83886
vm.watermark_scale_factor=100 
vm.swappiness = 1
vm.dirty_background_ratio = 10
vm.dirty_ratio = 80
vm.dirty_expire_centisecs = 500
vm.dirty_writeback_centisecs = 100
vm.vfs_cache_pressure = 500
vm.extfrag_threshold = 200
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_syn_retries = 2
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_max_syn_backlog = 65535
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_max_tw_buckets = 20000
net.ipv4.tcp_keepalive_time = 120
net.ipv4.tcp_keepalive_intvl = 5
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.core.somaxconn = 65535
net.core.rmem_max=16777216
net.core.wmem_max=16777216
net.ipv4.tcp_rmem=4096 87380 16777216
net.ipv4.tcp_wmem=4096 65536 16777216
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_window_scaling = 0
net.ipv4.tcp_sack = 0
net.core.netdev_max_backlog = 30000
net.ipv4.tcp_no_metrics_save=1
net.ipv4.tcp_max_orphans = 262144
fs.file-max = 6553600
kernel.watchdog_thresh=30
EOF

#sudo sysctl -p

1）保证系统可靠运行，保留可用内存
2）优先使用物理内存，仅可能规避swap分区的使用
3）优先脏页数据尽量写入磁盘
4）放大tcp和udp的缓冲区，提升tcp，udp的收发包的性能
5）增加文件句柄
6）调整优先使用buffer缓冲区和内存整理的平衡
7）调整为内存触发策略min,low,high以及调大宽度，提前为峰值业务保留多一点内存
8）及时关闭tcp的链接，对于wait状态的链接开启重用

压测后，测试观察：
1）磁盘swap分区，vmstat 1 1000
2）负载：uptime 负载
3）内存：free -h  和 smem
4）程序的运行时间和系统的运行时间
5）碎片化监控和zone各内存的分配情况