Many Linux users encounter a puzzling situation where the system actively uses swap space despite having considerable free RAM. This contradicts the common understanding that swap is only utilized when physical memory is exhausted.

Linux employs an advanced memory management strategy that considers several factors beyond just free memory:

• Swappiness parameter (0-100) controls swap tendency
• Kernel's proactive caching mechanism
• Memory page aging and access patterns

To view your current swappiness value:

cat /proc/sys/vm/swappiness

Typical default is 60, meaning the kernel will start swapping when memory usage reaches about 40%.

For systems with sufficient RAM, you might want to reduce swappiness:

# Temporary change
sudo sysctl vm.swappiness=10

# Permanent change
echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

In some cases, swap usage with free RAM is intentional:

• The kernel moves rarely-used pages to swap
• Leaves more RAM available for disk caching
• Prepares for potential memory spikes

Use these commands to get detailed memory insights:

# Detailed memory breakdown
free -h

# Process-level memory usage
top -o %MEM

# Page cache and slab info
cat /proc/meminfo

For high-performance systems with abundant RAM, you might consider:

# Disable all swap temporarily
sudo swapoff -a

# To re-enable:
sudo swapon -a

Note: This is generally not recommended for production systems.

For MySQL/MariaDB servers, we typically want minimal swapping:

# Add to /etc/sysctl.conf
vm.swappiness = 1
vm.dirty_ratio = 80
vm.dirty_background_ratio = 5

Many Linux users encounter a puzzling scenario where swap space shows significant activity despite having considerable free RAM. This contradicts the common understanding that swap only activates when physical memory is exhausted.

# Typical memory status output
$ free -h
              total        used        free      shared  buff/cache   available
Mem:           15Gi       5.3Gi       6.8Gi       512Mi       2.9Gi        9.2Gi
Swap:         2.0Gi       1.5Gi       512Mi

Modern Linux kernels employ sophisticated memory management strategies that go beyond simple RAM exhaustion scenarios:

• Swappiness Tuning: The kernel parameter vm.swappiness (default 60) influences swap behavior
• Inactive Memory: The kernel may proactively move rarely accessed pages to swap
• Memory Pressure: Even with free RAM, the kernel might use swap to maintain performance headroom

To understand your specific case, use these diagnostic commands:

# Check swappiness value
$ cat /proc/sys/vm/swappiness

# View detailed memory statistics
$ cat /proc/meminfo

# Identify processes using swap
$ sudo smem -t -k -s swap

If you want to adjust swap behavior, consider these solutions:

# Temporarily adjust swappiness (0-100)
$ sudo sysctl vm.swappiness=30

# Make permanent changes
$ echo "vm.swappiness=30" | sudo tee -a /etc/sysctl.conf

# Completely disable swap (not recommended)
$ sudo swapoff -a

In some cases, this behavior improves performance:

• When applications allocate memory but rarely use it
• For systems with fast SSD swap partitions
• In virtualized environments where balloon drivers operate

Always monitor performance metrics before making changes, as the Linux kernel's memory management is generally well-tuned for most workloads.