Re: [PATCH 0/2] hugetlb memcg accounting

Mike Kravetz
2023-10-01T23:28:20Z

On 09/27/23 14:47, Johannes Weiner wrote:
> On Wed, Sep 27, 2023 at 01:21:20PM +0200, Michal Hocko wrote:
> > On Tue 26-09-23 12:49:47, Nhat Pham wrote:
>
> So that if you use 80% hugetlb, the other memory is forced to stay in
> the remaining 20%, or it OOMs; and that if you don't use hugetlb, the
> group is still allowed to use the full 100% of its host memory
> allowance, without requiring some outside agent continuously
> monitoring and adjusting the container limits.

Jumping in late here as I was traveling last week. In addition, I want
to state my limited cgroup knowledge up front.

I was thinking of your scenario above a little differently. Suppose a
group is up and running at almost 100% memory usage. However, the majority
of that memory is reclaimable. Now, someone wants to allocate a 2M hugetlb
page. There is not 2MB free, but we could easily reclaim 2MB to make room
for the hugetlb page. I may be missing something, but I do not see how that
is going to happen. It seems like we would really want that behavior.
--
Mike Kravetz