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. -- Jens Axboe
