On 9/16/26 18:22, Davidlohr Bueso wrote: > On Wed, 16 Sep 2026, T.J. Mercier wrote: > >> I'm not sure these patches were motivated by Android (based on x86 >> focus in the commit message), but Davidlohr would have to comment on >> that. That's just where most of my experience comes from and what I >> can share details about. > > This series was motivated by exploring new use cases for dma-buf (such > as kvcache), not really for Android specifically. I was counting on > the cheap/one-time 2Mb attempt (current high order semantics) to not be > a problem for potential performance gains. As for the x86 I tested here, > basically because it's what I have on hand, I had no idea ROCm was a no-no > for system heaps.
Well the problem is that it does work, but gives you unstable performance and people see that as a bug while it is an intentional design decision made to keep the system heap driver independent. So yeah it's a trade off, it should just be properly documented. > I am fine dropping this effort. It's clearly good that we talked about this. When something is changed here I would rather say that we have some #ifdef CONFIG_ARM around the existing code and use the PMD_SIZE for all other platforms. If functionality isn't changed I think adding at least some notes that this only works optimal on 4k ARM platforms is clearly a good idea. Regards, Christian. > > Thanks, > Davidlohr
