On Wed 10-07-19 19:48:09, Minchan Kim wrote:

On Tue, Jul 09, 2019 at 11:55:19AM +0200, Michal Hocko wrote:

[...]

quoted

I am still not convinced about the SWAP_CLUSTER_MAX batching and the
udnerlying OOM argument. Is one pmd worth of pages really an OOM risk?
Sure you can have many invocations in parallel and that would add on
but the same might happen with SWAP_CLUSTER_MAX. So I would just remove
the batching for now and think of it only if we really see this being a
problem for real. Unless you feel really strong about this, of course.

I don't have the number to support SWAP_CLUSTER_MAX batching for hinting
operations. However, I wanted to be consistent with other LRU batching
logic so that it could affect altogether if someone try to increase
SWAP_CLUSTER_MAX which is more efficienty for batching operation, later.
(AFAIK, someone tried it a few years ago but rollback soon, I couldn't
rebemeber what was the reason at that time, anyway).

Then please drop this part. It makes the code more complex while any
benefit is not demonstrated.

quoted

Anyway the patch looks ok to me otherwise.

Acked-by: Michal Hocko <redacted>

Thanks!

-- 
Michal Hocko
SUSE Labs