Deflated

zcache

Finally, the third candidate, zcache [10], is a back end for a special type of virtual RAM known as transcendent memory. It is used for compressed intermediate file storage or for swapping out such files. Zswap is a simplified version of zcache. However, zcache is currently considered experimental. You activate this kernel feature by adding the zcache parameter to the GRUB configuration and rebooting the system.

Conclusions

All three methods are designed to avoid access to slower media. The three technologies achieve this with noticeable success; no impairments occurred in run-time tests. Whereas zram creates its own block device, zswap and zcache do without one and are already integrated into the Linux kernel as modules. On the basis of our observations, all three methods work with the Lempel-Ziv-Oberhumer (LZO) compression algorithm, but in principle, they also support alternative methods. A more effective use of memory can offer significant benefits, especially with smaller devices.

Infos

  1. zram: https://en.wikipedia.org/wiki/Zram
  2. "How to get hardware information with dmidecode command on Linux": https://www.tecmint.com/how-to-get-hardware-information-with-dmidecode-command-on-linux/
  3. DMI: https://www.dmtf.org/standards/dmi
  4. compcache: https://code.google.com/archive/p/compcache/
  5. zswap: https://www.kernel.org/doc/Documentation/vm/zswap.txt
  6. "Linux kernel memory management: Swap space": https://linuxhint.com/linux-memory-management-swap-space/
  7. "Optimizing Linux memory usage": https://linuxhint.com/optimizing-linux-memory-usage/
  8. zram: https://wiki.gentoo.org/wiki/Zram
  9. zramctl: http://karelzak.blogspot.co.za/2014/08/zramctl.html
  10. "How do I use/enable zcache?": https://askubuntu.com/questions/300685/how-do-i-use-enable-zcache
  11. The authors thank Gerold Rupprecht and Axel Beckert for their suggestions and appraisals in the run-up to the article.

The Author

Frank Hofmann works from Berlin, Geneva, and Cape Town as a developer, trainer, and author. He is also the coauthor of the Debian Package Management book (https://www.dpmb.org/index.en.html). Mandy Neumeyer has lived in South Africa for nine years, works in tourism, and is currently building up additional income as a digital nomad.

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