On Tue 31-01-23 09:32:27, David Hildenbrand wrote: > On 30.01.23 23:15, Jens Axboe wrote: > > On 1/30/23 3:12 PM, David Howells wrote: > > > John Hubbard <jhubbard@xxxxxxxxxx> wrote: > > > > > > > This is something that we say when adding pin_user_pages_fast(), > > > > yes. I doubt that I can quickly find the email thread, but we > > > > measured it and weren't immediately able to come up with a way > > > > to make it faster. > > > > > > percpu counters maybe - add them up at the point of viewing? > > > > They are percpu, see my last email. But for every 108 changes (on > > my system), they will do two atomic_long_adds(). So not very > > useful for anything but low frequency modifications. > > > > Can we just treat the whole acquired/released accounting as a debug > mechanism to detect missing releases and do it only for debug kernels? Yes, AFAIK it is just a debug mechanism for helping to find out issues with page pinning conversions. So I think we can put this behind some debugging ifdef. John? Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
