When deploying websites or applications, many webmasters and developers choose US cloud servers. These servers are relatively affordable, offer flexible configurations, and offer ample bandwidth, making them suitable for scenarios such as cross-border e-commerce, overseas independent websites, and gaming services. However, as project traffic increases or program complexity grows, server resource consumption rapidly increases. Failure to properly optimize memory and CPU can lead to performance degradation at best, and system lag or even crashes at worst.

　　Before optimizing, it's crucial to identify the bottleneck. Many people blindly expand capacity or change plans, ignoring the root cause of performance issues. Generally, server performance issues manifest themselves in excessive CPU usage, memory consumption, high I/O latency, and load imbalance. In Linux, commands like top, htop, free -m, vmstat 1, and iostat -x 1 can help you monitor key metrics like CPU load, memory usage, cache usage, and disk I/O in real time, providing a basis for subsequent optimization.

　　Ⅰ. Memory Optimization Tips

　　Memory is a critical factor affecting server stability. Many website crashes or application anomalies are often related to improper memory allocation. The following are common optimization methods:

　　1. Disable unnecessary processes from remaining in memory

　　After initially installing a US cloud server, the system automatically starts many services, such as postfix, rpcbind, and cups. If you only run web or database services, these background processes are completely unnecessary.

　　You can view system services using the following command:

systemctl list-unit-files --type=service

　　Then shut down irrelevant services:

systemctl disable postfix
systemctl stop postfix

　　This can free up significant memory space and reduce the boot load.

　　2. Adjust the Swap Policy

　　Swap is a mechanism in which the system temporarily writes some data to the hard disk when physical memory is insufficient. However, excessive use of swap can lead to a sharp decline in performance, as disk read and write speeds are much slower than memory.

　　You can adjust the swap policy by modifying the /etc/sysctl.conf file:

vm.swappiness=10

　　The default value is 60, and it is recommended to reduce it to 10 or 20 to allow the system to prioritize physical memory. After modification, execute:

sysctl -p

　　Effective immediately.

　　3. Clear cache and unused files properly

　　Linux systems automatically cache files and directories to speed up access, but excessive caching can lead to memory shortages. To clear the cache, run the following command:

sync; echo 3 > /proc/sys/vm/drop_caches

　　At the same time, regularly clean up logs and temporary files:

rm -rf /var/log/*.gz
rm -rf /tmp/*

　　This effectively frees up space and prevents the system from being slowed down by large amounts of logs.

　　4. Optimize Database Memory Usage

　　If your cloud server is running MySQL or MariaDB, it's recommended to optimize its memory parameters. For example, in /etc/my.cnf:

innodb_buffer_pool_size=512M
query_cache_size=64M
tmp_table_size=64M

　　A reasonable cache size can significantly improve query efficiency while preventing the database from consuming excessive memory.

　　II. CPU Optimization Techniques

　　The CPU is the "brain" of the server and determines processing power. Optimizing CPU performance relies on improving resource utilization and task scheduling efficiency.

　　1. Limiting CPU Usage of a Single Process

　　When a program experiences an anomaly (such as an infinite loop or computationally intensive task), it can instantly consume the CPU, causing the system to become unresponsive. To limit process usage, use the cpulimit command:

cpulimit -e php-fpm -l 60

　　This limits the CPU usage of the php-fpm process to no more than 60%.

　　2. Adjusting Process Priority

　　Use the nice or renice command to change the process priority to allow critical services (such as nginx and MySQL) more CPU resources:

renice -n -5 -p 1234

　　The smaller the value, the higher the priority.

　　3. Enable Multi-Core Parallel Optimization

　　Many US cloud servers offer multi-core CPUs by default, but not all applications can automatically take advantage of them.

• For Nginx, you can adjust it in the configuration file:

worker_processes auto;

• For PHP, you can use php-fpm multi-process mode;
• For databases, you can enable multithreaded queries or parallel replication.

　　4. Enable the Performance Scheduler

　　In Ubuntu or CentOS, you can improve performance by switching the CPU scheduling policy:

cpupower frequency-set -g performance

　　Change the default energy-saving mode to prioritize performance, ensuring the CPU always runs at its highest frequency.

　　III. Comprehensive System-Level Optimization

　　1. Use a Lightweight Software Stack

　　Choosing a lightweight web environment can significantly reduce resource consumption.

• Replace Apache with Nginx;
• Use MariaDB instead of MySQL;
• Use PHP-FPM instead of CGI mode.

　　These combinations offer significant advantages in performance and memory usage.

　　2. Enable Caching and CDN

　　Use Redis or Memcached to cache popular data at the website level to reduce database queries. Also, enable CDN acceleration to distribute static content to global nodes, which not only reduces server CPU load but also improves access speed.

　　3. Disable Unnecessary Scheduled Tasks

　　Use crontab -l to view current scheduled tasks and delete unnecessary or overly frequent scripts to prevent the system from running under high load every few minutes.

　　4. Use Monitoring Tools

　　Deploy monitoring tools such as Netdata, Zabbix, and Prometheus to track metrics like CPU, memory, I/O, and network latency in real time. Once problems are discovered, you can quickly identify the root cause.

　　Ⅳ. FAQ

　　Q1: What problems can occur if a US cloud server runs out of memory?

　　A: When memory is insufficient, the system will frequently invoke swaps or forcefully terminate processes, resulting in access delays, website crashes, or "Out of Memory" errors.

　　Q2: How can I troubleshoot high CPU usage?

　　A: Use top to view the highest-utilizing processes, then use ps aux to analyze the specific programs. If it's PHP or a database, check for issues like script loops and slow queries.

　　Q3: Will adjusting the CPU scheduling policy affect stability?

　　A: No. As long as the hardware temperature control is normal, using performance mode can significantly increase processing speed, but power consumption will increase slightly.

　　Q4: Is it necessary to purchase a higher-spec cloud server?

　　A: If, after optimization, CPU utilization continues to exceed 80% and memory utilization remains near 100%, you can consider upgrading the configuration. However, optimization is always the first priority.

　　Q5: Is it necessary to disable swap?

　　A: It's not recommended to completely disable it. A small amount (such as 1GB) can be reserved to deal with sudden memory overflows. Simply reduce the swap usage trend.

　　Q6: How can I automate the optimization process?

　　A: You can write a shell script to regularly clear the cache and restart the service, and integrate it with cron for automated maintenance.

　　Optimizing the memory and CPU of US cloud servers can not only improve the running speed of the website, but also extend the life of the server and save costs. The key to optimization lies in "reasonable allocation" and "dynamic adjustment" - neither let resources idle nor let the system overload. By shutting down useless processes, adjusting kernel parameters, and using cache and scheduling strategies properly, you can maximize the performance of the server under limited configuration. For small and medium-sized websites, optimization is often more cost-effective than upgrading the configuration; and for large business systems, performance optimization is the basis for ensuring high-concurrency and stable operation.