On 07/31/2018 05:04 PM, Christian König wrote: > Am 31.07.2018 um 10:58 schrieb Zhang, Jerry (Junwei): >> On 07/31/2018 04:13 PM, Christian König wrote: >>> Am 31.07.2018 um 10:05 schrieb Zhang, Jerry (Junwei): >>>> On 07/31/2018 03:03 PM, Christian König wrote: >>>>> Am 31.07.2018 um 08:58 schrieb Zhang, Jerry (Junwei): >>>>>> On 07/30/2018 06:47 PM, Christian König wrote: >>>>>>> Am 30.07.2018 um 12:02 schrieb Junwei Zhang: >>>>>>> [SNIP] >>>>>>> Please double check if that is still up to date. >>>>>> >>>>>> We may have to replace drm_gem_object_reference() with drm_gem_object_get(). >>>>>> >>>>>> On 2nd thought, do we really need to do reference every time? >>>>> >>>>> Yes, that's a must have. Otherwise the handle could be freed and reused already when we return. >>>>> >>>>>> if UMD find the same gem object for 3 times, it also need to explicitly free(put) that object for 3 times? >>>>> >>>>> Correct yes. Thinking more about this the real problem is to translate the handle into a structure in libdrm. >>>>> >>>>> Here we are back to the problem Marek and Michel has been working on for a while that we always need to be able to translate a handle into a bo structure..... >>>>> >>>>> So that needs to be solved before we can upstream the changes. >>>> >>>> Thanks for your info. >>>> It's better to fix that before upstream. >>> >>> Thinking more about this the hash currently used in libdrm is not adequate any more. >>> >>> E.g. we now need to be able to find all BOs based on their handle. Since the handles are dense either an r/b tree or a radix tree now sounds like the best approach to me. >> >> Not sure the exact reason that we added hash table in libdrm. > > The reason for that was that when a kernel function returns a handle we need to make sure that we always use the same struct amdgpu_bo for it. > > Otherwise you run into quite some problems with syncing etc... Thanks for your explanation. > >> But it really costs much less time than calling IOCTL to find BO by their handles. > > Well we could just completely drop the kernel implementation and use an userspace implementation. Do you mean to implement finding bo by cpu address in libdrm completely? e.g. to create a tree to manage bo handle in libdrm? Jerry > > And yes I agree when we need a tree anyway it would probably be faster than calling the IOCTL to find the BO. > > Christian. > >> >> In this case, UMD seems not to be able to get BO handle and try to verify it by cpu address then. >> In another word, UMD would like to find if the memory is created as BO or system memory, I suppose. >> >> Regards, >> Jerry >> >> >>> >>> Christian. >>> >>>> >>>> Regards, >>>> Jerry >>> >> _______________________________________________ >> amd-gfx mailing list >> amd-gfx at lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/amd-gfx >
