Re: [RFC PATCH 3/3] mm, proc: report PR_SET_THP_DISABLE in proc

On Tue 27-11-18 07:50:08, William Kucharski wrote:

quoted

On Nov 27, 2018, at 6:17 AM, Michal Hocko [off-list ref] wrote:

This is only about the process wide flag to disable THP. I do not see
how this can be alighnement related. I suspect you wanted to ask in the
smaps patch?

No, answered below.

quoted

quoted

I'm having to deal with both these issues in the text page THP
prototype I've been working on for some time now.

Could you be more specific about the issue and how the alignment comes
into the game? The only thing I can think of is to not report VMAs
smaller than the THP as eligible. Is this what you are looking for?

Basically, if the faulting VA is one that cannot be mapped with a THP
due to alignment or size constraints, it may be "eligible" for THP
mapping but ultimately can't be.

I was just double checking that this was meant to be more of a check done
before code elsewhere performs additional checks and does the actual THP
mapping, not an all-encompassing go/no go check for THP mapping.

I am still not sure I follow you completely here. This just reports
per-task eligibility. The system wide eligibility is reported via sysfs
and the per vma eligibility is reported via /proc/<pid>/smaps.

-- 
Michal Hocko
SUSE Labs