Re: [PATCH] mm, memcg: Add memory.transparent_hugepage_disabled

[Chris Down]

Hui Zhu writes:
> /sys/kernel/mm/transparent_hugepage/enabled is the only interface to
> control if the application can use THP in system level.
> Sometime, we would not want an application use THP even if
> transparent_hugepage/enabled is set to "always" or "madvise" because
> thp may need more cpu and memory resources in some cases.
>
> This commit add a new interface memory.transparent_hugepage_disabled
> in memcg.
> When it set to 1, the application inside the cgroup cannot use THP
> except dax.

I'm against this patch even in the abstract -- this adds an extremely niche use 
case to a general interface, and there are plenty of ways to already indicate 
THP preference.

Perhaps there is some new interface desirable for your use case, but adding a 
new global file to memcg certainly isn't it.