[memory, zram] How to enable zram

How to enable zram

This document is following the procedures metioned by [1]. 

When memory was low, system would unresponsive and even freeze. ZRAM creates RAM based block storage named /dev/zram0 (or 1, 2, 3, etc). Pages written there are compressed and stored in memory. This allows for very fast I/O and the compression savings provide additional memory. See the document in detail.

1. Quick

sudo apt install zram-tools sudo vi /etc/default/zramswap File: /etc/default/zramswap ... PERCENT=50   # 50% ram use zram .... sudo zramswap stop sudo zramswap start sudo zramswap status # Kernel sudo vi /etc/sysctl.conf File: /etc/sysctl.conf vm.vfs_cache_pressure=500 vm.swappiness=100 vm.dirty_background_ratio=1 vm.dirty_ratio=50 sudo sysctl --system  # enable the parameters

2. Procedure

2.1. Before

Verification

free -m sudo cat /proc/swaps

2.2. Install zram-tool

sudo apt install zram-tools

E.g.

Check

sudo cat /proc/swaps

zramswap status

2.3. Config

sudo vi /etc/default/zramswap File: /etc/default/zramswap ... PERCENT=50   # 50% ram use zram .... sudo zramswap stop sudo zramswap start sudo zramswap status

E.g.

2.4. Verification

sudo zramswap status

E.g.

3. Setup Kernel parameters

3.1. Before

sudo cat /proc/swaps

3.2. Setup

sudo vi /etc/sysctl.conf File: /etc/sysctl.conf vm.vfs_cache_pressure=500 vm.swappiness=100 vm.dirty_background_ratio=1 vm.dirty_ratio=50 sudo sysctl --system

E.g.

3.3. Verification

sudo cat /proc/swaps

4. References

1. https://haydenjames.io/raspberry-pi-performance-add-zram-kernel-parameters/

2. https://www.kernel.org/doc/Documentation/blockdev/zram.txt