On 20/08/2024 17:30, Barry Song wrote: > Hi Usama, > thanks! I can't judge if we need this partially_mapped flag. but if we > need, the code > looks correct to me. I'd like to leave this to David and other experts to ack. > Thanks for the reviews! > an alternative approach might be two lists? one for entirely_mapped, > the other one > for split_deferred. also seems ugly ? > That was my very first prototype! I shifted to using a bool which I sent in v1, and then a bit in _flags_1 as David suggested. I believe a bit in _flags_1 is the best way forward, as it leaves the most space in folio for future work. > On the other hand, when we want to extend your patchset to mTHP other than PMD- > order, will the only deferred_list create huge lock contention while > adding or removing > folios from it? > Yes, I would imagine so. the deferred_split_queue is per memcg/node, so that helps. Also, this work is tied to khugepaged. So would need some thought when doing it for mTHP. I would imagine doing underused shrinker for mTHP would be less beneficial compared to doing it for 2M THP. But probably needs experimentation. Thanks
