On 01/03/2013 01:50 PM, Terje Bergström wrote: > On 03.01.2013 05:31, Mark Zhang wrote: >> Sorry I didn't get it. Yes, in current design, you can pin all mem >> handles in one time but I haven't found anything related with "locking >> only once per submit". >> >> My idea is: >> - remove "job->addr_phys" >> - assign "job->reloc_addr_phys" & "job->gather_addr_phys" separately >> - In "pin_job_mem", just call "host1x_memmgr_pin_array_ids" twice to >> fill the "reloc_addr_phy" & "gather_addr_phys". >> >> Anything I misunderstood? > > The current design uses CMA, which makes pinning basically a no-op. When > we have IOMMU support, pinning requires calling into IOMMU. Updating > SMMU tables requires locking, and probably maintenance before SMMU code > also requires its own locked data tables. For example, preventing > duplicate pinning might require a global table of handles. > > Putting all of the handles in one table allows doing duplicate detection > across cmdbuf and reloc tables. This allows pinning each buffer exactly > once, which reduces number of calls to IOMMU. > Thanks Terje. Yes, I understand IOMMU will bring in more operations. But I'm not convinced that separating 2 arrays have lots of overheads than putting them into one array. But it doesn't matter, after the IOMMU support version released, I can read this part of codes again. Let's talk about this at that time. >> "host1x_cma_pin_array_ids" doesn't return negative value right now, so >> maybe you need to take a look at it. > > True, and also a consequence of using CMA: pinning can never fail. With > IOMMU, pinning can fail. Got it. Agree. > > Terje > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
