ZRAM related kernel configuration

ZRAM is enabled by default. In dialog «Storage & File System Options» you may disable it. If you modify kernel settings that would degrade ZRAM’s performance, or the performance of a system without ZRAM (in case ZRAM is disabled), a warning will be displayed when confirming such kernel settings.

List of ZRAM related settings

Optimize swap file and ZRAM usage

Related kernel setting: vm.swappiness

If you have left ZRAM enabled (default), this setting changes the swappiness from the default of 60 to the recommended value of 180. If you have ZRAM disabled, this setting changes swappiness to 1, which conserves RAM for active applications to improve system responsiveness, but leaves less RAM available for kernel operations such as caching file system metadata and managing network buffers. Unchecking the setting will use the kernel default in all cases.

Default: activated if zram is enabled, else if system as more than 24 GB RAM.

Disable Zswap Cache Layer

Related kernel parameter: zswap.enabled=0

Disables Zswap’s intermediary cache, allowing direct use of swap devices like ZRAM.

Default: activated if zram is enabled

Disable Swap Readahead

Related kernel setting: vm.page-cluster 3 ⇨ 0

The system reads only one page at a time from swap, potentially reducing initial latency when accessing swapped-out pages. This is advantageous when using ZRAM, as ZRAM provides fast access to swap space. Reading only the required pages can improve performance without the overhead of prefetching additional pages.

Default: activated if zram is enabled

Disable Extra Memory Reclaim

Related kernel setting: vm.watermark_boost_factor 15000 ⇨ 0

This reduces reclaim activity during memory fragmentation when high-order memory allocations are less critical. This can optimize memory management for systems using ZRAM. Since ZRAM reduces the need for high-order memory allocations, the extra memory reclaim becomes unnecessary, improving overall performance.

Default: activated if zram is enabled

Maintain free memory

Related kernel setting: vm.watermark_scale_factor 10/3000 ⇨ 125/3000

Make the Kernel Swap Thread more aggressive in maintaining free memory. This helps prevent applications from entering direct memory reclaim, enhancing system responsiveness under memory pressure. This is particularly beneficial for systems with ZRAM, because it allows the system to better utilize ZRAM’s fast swap capabilities by maintaining more free memory and reducing allocation stalls.

Default: activated if zram is enabled