On Tue, 27 Jun 2023, David Hildenbrand wrote: > On 27.06.23 06:44, Hugh Dickins wrote: > > On Mon, 26 Jun 2023, Vishal Moola (Oracle) wrote: > > > >> The MM subsystem is trying to shrink struct page. This patchset > >> introduces a memory descriptor for page table tracking - struct ptdesc. > > ... > >> 39 files changed, 686 insertions(+), 455 deletions(-) > > > > I don't see the point of this patchset: to me it is just obfuscation of > > the present-day tight relationship between page table and struct page. > > > > Matthew already explained: > > > >> The intent is to get ptdescs to be dynamically allocated at some point > >> in the ~2-3 years out future when we have finished the folio project ... > > > > So in a kindly mood, I'd say that this patchset is ahead of its time. > > But I can certainly adapt to it, if everyone else sees some point to it. > > I share your thoughts, that code churn which will help eventually in the far, > far future (not wanting to sound too pessimistic, but it's not going to be > there tomorrow ;) ). > > However, if it's just the same as the other conversions we already did (e.g., > struct slab), then I guess there is no reason to stop now -- the obfuscation > already happened. > > ... or is there a difference regarding this conversion and the previous ones? I was aware of the struct slab thing, didn't see much point there myself either; but it was welcomed by Vlastimil, and barely affected outside of slab allocators, so I had no reason to object. You think that if a little unnecessary churn (a *lot* of churn if you include folios, which did save some repeated calls to compound_head()) has already occurred, that's a good precedent for allowing more and more? My opinion happens to differ on that. Hugh
