Am 02.08.2018 um 08:20 schrieb Zhang, Jerry (Junwei): > On 08/02/2018 08:00 AM, Marek Olšák wrote: >> On Wed, Aug 1, 2018 at 2:29 PM, Christian König >> <christian.koenig at amd.com> wrote: >>> Am 01.08.2018 um 19:59 schrieb Marek Olšák: >>>> [SNIP] >>> >>> Compared to what the kernel needs to do for updating the page tables >>> it is >>> less than 1% of the total work. >>> >>> The real question is if it wouldn't be simpler to use a tree for the >>> handles. Since the handles are dense you can just use an unbalanced >>> tree >>> which is really easy. >>> >>> For a tree of the CPU mappings we would need an r/b interval tree, >>> which is >>> hard to implement and quite some overkill. >>> >>> Do you have any numbers how many BOs really get a CPU mapping in a real >>> world application? >> >> Without our suballocator, we sometimes exceeded the max. mmap limit >> (~64K). It should be much less with the suballocator with 128KB slabs, >> probably a few thousands. > > Is there a way to verify that it has performance issue if moving the > cpu mapping in libdrm hash table > from kernel side? Going to take a look at this, but I have the feeling that the CPU overhead we need to add in userspace isn't that much. > > AFAIW, only one game will use that with close OGL. Well, I would also say that this is a bug in the game and should be fixed there. Christian. > > Regards, > Jerry > >> >> Marek >>
