On 15.05.25 17:45, Liam R. Howlett wrote:
* David Hildenbrand <david@xxxxxxxxxx> [250515 10:44]:
On 15.05.25 16:40, Lorenzo Stoakes wrote:
Overall I feel this series should _DEFINITELY_ be an RFC. This is pretty
outlandish stuff and needs discussion.
You're basically making it so /sys/kernel/mm/transparent_hugepage/enabled =
never is completely ignored and overridden.
I thought I made it very clear during earlier discussions that never means
never.
I also thought so, but the comments later made here [1] seem to
contradict that?
It's ... complicated.
It seems "never" means "default_no" and not actually "never"?
We should consider these system toggles a single set of toggles that define a
state, and not individual toggles that overwrite each other.
If you say
/sys/kernel/mm/transparent_hugepage/enabled = never
and
/sys/kernel/mm/transparent_hugepage/hugepages-2048kB/enabled = always
instead of the *default*
/sys/kernel/mm/transparent_hugepage/hugepages-2048kB/enabled = inherit
the admin explicitly stats "I want the system behavior for 2048kB not to be configured using
/sys/kernel/mm/transparent_hugepage/enabled". That's an admin decision, not a
per-process overwrite or whatever.
Maybe the global/system toggles need to affect the state of each other?
That is, if /sys/kernel/mm/transparent_hugepage/enabled is never and you
set /sys/kernel/mm/transparent_hugepage/hugepages-2048kB/enabled to
madvise, it should not leave /sys/kernel/mm/transparent_hugepage/enabled
as never.
I recall we discussed that, but there was also a catch to that. :(
--
Cheers,
David / dhildenb
