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Comment by deckiedan | Hacker News Reader

All those quoted performance improvements sound great - but what kind of Real World workload or environment would one need to be in to see this in action? Anywhere when swapping? Or does it need to be with special hardware? Would a SSD backed low-memory VM be improved?

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All sorts of cloud hosting things would benefit from this. The ability to swap in and out very fast allows you to run more containers or vms on the same machine in cases where only a percentage of those instances are utilized at any given time but even if one is swapped out it must be able to swap in and respond with reasonable latency.

Any kind of "serverless" hosting or any architecture where you have a container per user would benefit from this kind of development.

If nvme swap gets faster too with huge pages then testing a whole microservice swarm on a local dev machine might benefit from it when the currently idle services can be swapped more swiftly while something chews on data.

> but what kind of Real World workload or environment would one need to be in to see this in action?

Hmm, Facebook perhaps.

Emedded devices tend to use zswap/zram which [yet] don't support THP, as far as I know. For instance, take a look at zswap_frontswap_store():

         /* THP isn't supported */ 
         if (PageTransHuge(page)) { 
                 ret = -EINVAL; 
                 goto reject; 
         }

Once zswap [and, perhaps, zram] gain THP swap out/in support, embedded devices [some of which use swap quite heavily] should also see a considerable performance improvement.

P.S. I didn't check the patch set, may be zswap THP support is already in there.

-ss

A followup: zswap THP support is not implemented yet. Huang Ying agreed that it would be interesting to have it, but it's not on his TODO list as of now.

-ss

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