Hi Daniel, On Wed, 18 Nov 2020 at 13:16, Daniel Vetter <daniel@xxxxxxxx> wrote: > > On Wed, Nov 18, 2020 at 3:40 AM John Stultz <john.stultz@xxxxxxxxxx> wrote: > > On Fri, Nov 13, 2020 at 12:39 PM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > On Thu, Nov 12, 2020 at 08:11:02PM -0800, John Stultz wrote: > > > > On Thu, Nov 12, 2020 at 1:32 AM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > On Thu, Nov 12, 2020 at 11:09:04AM +0530, Sumit Semwal wrote: > > > > > > On Tue, 10 Nov 2020 at 09:19, John Stultz <john.stultz@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > Hey All, > > > > > > > So just wanted to send my last revision of my patch series > > > > > > > of performance optimizations to the dma-buf system heap. > > > > > > > > > > > > Thanks very much for your patches - I think the first 5 patches look good to me. > > > > > > > > > > > > I know there was a bit of discussion over adding a new system-uncached > > > > > > heap v/s using a flag to identify that; I think I prefer the separate > > > > > > heap idea, but lets ask one last time if any one else has any real > > > > > > objections to it. > > > > > > > > > > > > Daniel, Christian: any comments from your side on this? > > > > > > > > > > I do wonder a bit where the userspace stack for this all is, since tuning > > > > > allocators without a full stack is fairly pointless. dma-buf heaps is a > > > > > bit in a limbo situation here it feels like. > > > > > > > > As mentioned in the system-uncached patch: > > > > Pending opensource users of this code include: > > > > * AOSP HiKey960 gralloc: > > > > - https://android-review.googlesource.com/c/device/linaro/hikey/+/1399519 > > > > - Visibly improves performance over the system heap > > > > * AOSP Codec2 (possibly, needs more review): > > > > - https://android-review.googlesource.com/c/platform/frameworks/av/+/1360640/17/media/codec2/vndk/C2DmaBufAllocator.cpp#325 > > > > > > > > Additionally both the HiKey, HiKey960 grallocs and Codec2 are already > > > > able to use the current dmabuf heaps instead of ION. > > > > > > > > So I'm not sure what you mean by limbo, other than it being in a > > > > transition state where the interface is upstream and we're working on > > > > moving vendors to it from ION (which is staged to be dropped in 5.11). > > > > Part of that work is making sure we don't regress the performance > > > > expectations. > > > > > > The mesa thing below, since if we test this with some downstream kernel > > > drivers or at least non-mesa userspace I'm somewhat worried we're just > > > creating a nice split world between the android gfx world and the > > > mesa/linux desktop gfx world. > > > > > > But then that's kinda how android rolls, so *shrug* > > > > > > > > Plus I'm vary of anything related to leaking this kind of stuff beyond the > > > > > dma-api because dma api maintainers don't like us doing that. But > > > > > personally no concern on that front really, gpus need this. It's just that > > > > > we do need solid justification I think if we land this. Hence back to > > > > > first point. > > > > > > > > > > Ideally first point comes in the form of benchmarking on android together > > > > > with a mesa driver (or mesa + some v4l driver or whatever it takes to > > > > > actually show the benefits, I have no idea). > > > > > > > > Tying it with mesa is a little tough as the grallocs for mesa devices > > > > usually use gbm (gralloc.gbm or gralloc.minigbm). Swapping the > > > > allocation path for dmabuf heaps there gets a little complex as last I > > > > tried that (when trying to get HiKey working with Lima graphics, as > > > > gbm wouldn't allocate the contiguous buffers required by the display), > > > > I ran into issues with the drm_hwcomposer and mesa expecting the gbm > > > > private handle metadata in the buffer when it was passed in. > > > > > > > > But I might take a look at it again. I got a bit lost digging through > > > > the mesa gbm allocation paths last time. > > > > > > > > I'll also try to see if I can find a benchmark for the codec2 code > > > > (using dmabuf heaps with and without the uncached heap) on on db845c > > > > (w/ mesa), as that is already working and I suspect that might be > > > > close to what you're looking for. > > > > > > tbh I think trying to push for this long term is the best we can hope for. > > > > > > Media is also a lot more *meh* since it's deeply fragmented and a lot less > > > of it upstream than on the gles/display side. > > > > > > I think confirming that this at least doesn't horrible blow up on a > > > gralloc/gbm+mesa stack would be useful I think. > > > > Sorry, I'm still a little foggy on precisely what you're suggesting here. > > > > The patch stack I have has already been used with db845c (mesa + > > gbm_grallloc), with the codec2 (sw decoders) using dmabuf heaps. > > So no blowing up there. And I'm working with Hridya to find a > > benchmark for codec2 so we can try to show the performance delta. > > > > However, if you're wanting a dma-buf gralloc implementation with mesa, > > that may be a little tougher to do, but I guess I can give it a go. > > > > Hopefully this will address concerns about the system-uncached heap > > patch (the last two patches in this series)? > > > > In the meantime I hope we can queue the first five patches, as it > > would be nice to get the code rearranging in as there are others > > trying to stage their own heaps, and I'd like to avoid dragging that > > churn out for too long (in addition to improving the allocation > > performance). Those changes have no ABI implications. > > Maybe I'm also misunderstanding what dma-buf heaps is used for in > Android, at least usually. I thought it's used to allocate all the > winsys/shared buffers through gralloc (at least in the blobby stacks), > to handle the allocation constraints problem. In the open stacks we > don't seem to have a platform with both mesa and v4l (or some other > codec) with "interesting" allocations constraints, so no one using > that gralloc+dma-buf heaps combo for what it was meant for. Hence why > I'm a bit vary that we're creating something here which just misses > the point a bit when we try to actually use it (in that glorious > forever-future world where an android platform has enough drivers in > upstream to do so). > > For other "this solves a system problem" we tend to be quite a bit > more picky with the demonstration use case, to make sure we're > actually creating something that solves the problem in reality. > > But it also looks like Android's just not there yet, so *shrug* ... For me, looking at the first 5 patches (listed below, for quick reference), they are only doing code reorganisation and minor updates for already existing heaps, and no ABI change, I am not able to clearly see your objection here. To me, these seem to be required updates that the existing system heap users can benefit from. dma-buf: system_heap: Rework system heap to use sgtables instead of pagelists dma-buf: heaps: Move heap-helper logic into the cma_heap implementation dma-buf: heaps: Remove heap-helpers code dma-buf: heaps: Skip sync if not mapped dma-buf: system_heap: Allocate higher order pages if available If we talk about the last two patches - the ones that add system uncached heap, I somewhat agree that we should be able to show the performance gains with this approach (which has been in use on ION and in devices) using dma-buf gralloc or similar. We can discuss the system-uncached heap when the dma-buf gralloc or similar demonstration for performance benefits is done, but I am inclined to push these 5 patches listed above through. Best, Sumit. > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch
