9 ms·
Red Hat memory optimisations and Riak performance
- mitchell_h 11y agoHas anyone actually run into a situation where THP is a benefit? I've run into enough memory slow downs by transparent huge pages that it's just a default to turn it off on all builds. I've never seen a production work load that has had any performance gain from THP. Same with numa.
- feld 11y agoYes, someone has been working on upstreaming 1GB SuperPages to FreeBSD because it dramatically increased the performance of their firewall appliances. https://lists.freebsd.org/pipermail/freebsd-hackers/2014-November/046449.html https://lists.freebsd.org/pipermail/freebsd-hackers/2014-Nov... These large (>4K) pages definitely have their uses.
- bonzini 11y agoTHP was introduced for KVM, and has huge benefits there. In fact I suggest that you set /sys/kernel/mm/transparent_hugepage/enabled to "madvise" rather than "never". This was applications that like their hugepages can still enable it manually.
- jermo 11y agoThey're not the only ones running into issues with TPH and numa. For more suggestions to reduce jitter on Linux see Gil Tene's (Azul) advice: http://highscalability.com/blog/2015/4/8/the-black-magic-of-systematically-reducing-linux-os-jitter.html http://highscalability.com/blog/2015/4/8/the-black-magic-of-... Namely: - Turn THP (Transparent Huge Pages) OFF. - Set vm.min_free_kbytes to AT LEAST 1GB (8GB on larger systems). - Set Swappiness to 0. - Set zone_reclaim_mode to 0.
- geidies 11y agoGood advise - but a swappiness = 0 setting can bite you as well. See an explanation in http://www.chinanetcloud.com/blog/attack-of-the-killer-kernel-change-swappiness http://www.chinanetcloud.com/blog/attack-of-the-killer-kerne... and why we set swappiness = 1.
- kokey 11y agoIt is also interesting to see a company using elasticsearch and riak together. I have considered looking into that combination after having some grief with riak 2.0 with a bundled in Solr.