Re: [PATCH mm v3] memcg: enable memory accounting in __alloc_pages_bulk

On Wed, Oct 13, 2021 at 10:16 AM Michal Hocko [off-list ref] wrote:

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If this is really that complicated (I haven't tried) then it would be
much more simple to completely skip the bulk allocator for __GFP_ACCOUNT
rather than add a tricky code. The bulk allocator is meant to be used
for ultra hot paths and memcg charging along with the reclaim doesn't
really fit into that model anyway. Or are there any actual users who
really need bulk allocator optimization and also need memcg accounting?

Bulk allocator is being used for vmalloc and we have several
kvmalloc() with __GFP_ACCOUNT allocations.

Do we really need to use bulk allocator for these allocations?
Bulk allocator is an bypass of the page allocator for performance reason
and I can see why that can be useful but considering that the charging
path can imply some heavy lifting is all the code churn to make bulk
allocator memcg aware really worth it? Why cannot we simply skip over
bulk allocator for __GFP_ACCOUNT. That would be a trivial fix.
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Actually that might be the simplest solution and I agree to skip bulk
allocator for __GFP_ACCOUNT allocations.