On Sat, Oct 21, 2017 at 12:08 AM, Michal Hocko <mhocko@xxxxxxxx> wrote: > On Wed 18-10-17 17:31:23, Balbir Singh wrote: >> With HMM, we can have either public or private zone >> device pages. With private zone device pages, they should >> show up as swapped entities. For public zone device pages >> the smaps output can be confusing and incomplete. >> >> This patch adds a new attribute to just smaps to show >> device memory usage. > > As this will become user API which we will have to maintain for ever I > would really like to hear about who is going to use this information and > what for. This is something I observed when running some tests with HMM/CDM. The issue I had was that there was no visibility of what happened to the pages after the following sequence 1. malloc/mmap pages 2. migrate_vma() to ZONE_DEVICE (hmm/cdm space) 3. look at smaps If we look at smaps after 1 and the pages are faulted in we can see the pages for the region, but at point 3, there is absolutely no visibility of what happened to the pages. I thought smaps is a good way to provide the visibility as most developers use that interface. It's more to fix the inconsistency I saw w.r.t visibility and accounting. Balbir Singh. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
