Re: [PATCH RFC] mm/madvise: introduce MADV_POPULATE to prefault/prealloc memory

Michal Hocko
2021-02-22T12:49:26Z

I am slowly catching up with this thread.

On Fri 19-02-21 09:20:16, David Hildenbrand wrote:
[...]
> So if we have zero, we write zero. We'll COW pages, triggering a write fault
> - and that's the only good thing about it. For example, similar to
> MADV_POPULATE, nothing stops KSM from merging anonymous pages again. So for
> anonymous memory the actual write is not helpful at all. Similarly for
> hugetlbfs, the actual write is not necessary - but there is no other way to
> really achieve the goal.

I really do not see why you care about KSM so much. Isn't KSM an
explicit opt-in with a fine grained interface to control which memory to
KSM or not?
--
Michal Hocko
SUSE Labs