Am 01.08.2018 um 19:39 schrieb Marek Olšák: > On Wed, Aug 1, 2018 at 2:32 AM, Christian König > <christian.koenig at amd.com> wrote: >> Am 01.08.2018 um 00:07 schrieb Marek Olšák: >>> Can this be implemented as a wrapper on top of libdrm? So that the >>> tree (or hash table) isn't created for UMDs that don't need it. >> >> No, the problem is that an application gets a CPU pointer from one API and >> tries to import that pointer into another one. >> >> In other words we need to implement this independent of the UMD who mapped >> the BO. > Yeah, it could be an optional feature of libdrm, and other components > should be able to disable it to remove the overhead. The overhead is negligible, the real problem is the memory footprint. A brief look at the hash implementation in libdrm showed that this is actually really inefficient. I think we have the choice of implementing a r/b tree to map the CPU pointer addresses or implement a quadratic tree to map the handles. The later is easy to do and would also allow to get rid of the hash table as well. Christian. > > Marek
