On 19/08/2024 09:52, Barry Song wrote: > On Mon, Aug 19, 2024 at 8:33 PM Barry Song <21cnbao@xxxxxxxxx> wrote: >> >> On Mon, Aug 19, 2024 at 8:28 PM David Hildenbrand <david@xxxxxxxxxx> wrote: >>> >>> On 18.08.24 09:58, Barry Song wrote: >>>> Hi Andrew, David, Usama, >>>> >>>> I'm attempting to rebase this series on top of Usama's >>>> [PATCH v3 0/6] mm: split underutilized THPs[1] >>>> >>>> However, I feel it is impossible and we might be tackling things >>>> in the wrong order. >>> >>> Is just the ordering suboptimal (which can/will get resolved one way or >>> the other), or is there something fundamental that will make this series >>> here "impossible"? >> >> i think it is just the ordering suboptimal. Ideally, mTHP counters can go >> first, then the new partially_mapped feature will rebase on top of >> mTHP counters. > > Sorry, please allow me to ramble a bit more. > > The nr_split_deferred counter is straightforward and simple without the > partially_mapped feature. Each time we enter split_list, we increment by > 1, and when we leave, we decrement by 1. > > With the new partially_mapped feature, we can enter split_list without > actually being partially_mapped. If the MTHP counter series is processed > first, the partially_mapped series can handle all cases while properly > clearing and setting the partially_mapped flag. These flag operations > need to be handled carefully. > Currently, I notice that Usama's series is clearing the flag unconditionally > in all cases. > > In simple terms, mTHP counters are just a counting mechanism that > doesn't introduce new features. However, partially_mapped is a new > feature. A better approach might be to handle the counters first, then > ensure that the new feature doesn't break the counter. > I am ok if the series needs to be reversed, I think the difficulty is for Andrew to tackle my series, yours and Yu Zhaos, which all seem to be touching the same code, so whatever makes it easier for Andrew I am happy with it. >> >>> >>> -- >>> Cheers, >>> >>> David / dhildenb > > Thanks > Barry
