Disable automatic transparent hugepages

[aermakov-zalando]

Transparent hugepages are problematic and the common recommendation is to disable them. Setting the corresponding flag to madvise disables the fully-automatic behaviour but allows applications to opt-in by using mmap.

[mdedetrich]

For reference, I became aware of this when experiencing occasional severe latency spikes in redis, latency doctor in redis gave this as a first message

I have a few advices for you:

I detected a non zero amount of anonymous huge pages used by your process. This creates very serious latency events in different conditions, especially when Redis is persisting on disk. To disable THP support use the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled', make sure to also add it into /etc/rc.local so that the command will be executed again after a reboot. Note that even if you have already disabled THP, you still need to restart the Redis process to get rid of the huge pages already created.

[aermakov-zalando]

👍

[szuecs]

👍

[szuecs]

Thanks @mdedetrich