| Message ID | 20210206054748.378300-1-john.stultz@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [RFC,1/2] dma-buf: dma-heap: Provide accessor to get heap name | expand |
On Mon, Feb 8, 2021 at 2:08 AM Daniel Vetter <daniel@ffwll.ch> wrote: > On Sat, Feb 06, 2021 at 05:47:48AM +0000, John Stultz wrote: > > By default dma_buf_export() sets the exporter name to be > > KBUILD_MODNAME. Unfortunately this may not be identical to the > > string used as the heap name (ie: "system" vs "system_heap"). > > > > This can cause some minor confusion with tooling, and there is > > the future potential where multiple heap types may be exported > > by the same module (but would all have the same name). > > > > So to avoid all this, set the exporter exp_name to the heap name. > > > > Cc: Daniel Vetter <daniel@ffwll.ch> > > Cc: Sumit Semwal <sumit.semwal@linaro.org> > > Cc: Liam Mark <lmark@codeaurora.org> > > Cc: Chris Goldsworthy <cgoldswo@codeaurora.org> > > Cc: Laura Abbott <labbott@kernel.org> > > Cc: Brian Starkey <Brian.Starkey@arm.com> > > Cc: Hridya Valsaraju <hridya@google.com> > > Cc: Suren Baghdasaryan <surenb@google.com> > > Cc: Sandeep Patil <sspatil@google.com> > > Cc: Daniel Mentz <danielmentz@google.com> > > Cc: Ørjan Eide <orjan.eide@arm.com> > > Cc: Robin Murphy <robin.murphy@arm.com> > > Cc: Ezequiel Garcia <ezequiel@collabora.com> > > Cc: Simon Ser <contact@emersion.fr> > > Cc: James Jones <jajones@nvidia.com> > > Cc: linux-media@vger.kernel.org > > Cc: dri-devel@lists.freedesktop.org > > Signed-off-by: John Stultz <john.stultz@linaro.org> > > Looks reasonable to me. > > I guess the main worry is "does this mean heap names become uapi", in > which case I'm maybe not so sure anymore how this will tie into the > overall gpu memory accounting story. > > Since for dma-buf heaps one name per buffer is perfectly fine, since > dma-buf heaps aren't very dynamic. But on discrete gpu drivers buffers > move, so baking in the assumption that "exporter name = resource usage for > this buffer" is broken. I suspect I'm missing a subtlety in what you're describing. My sense of the exporter name doesn't account for a buffer's usage, it just describes what code allocated it and implicitly which dmabuf_ops handles it. Maybe could you give a more specific example of what you're hoping to avoid? To me this patch is mostly just a consistency/least-surprise thing, so the heaps exporter name matches the string used for the heap's chardev device (the interface used to allocate it) in output like debugfs/dma_buf/bufinfo. thanks -john
On Mon, Feb 8, 2021 at 10:03 PM Sumit Semwal <sumit.semwal@linaro.org> wrote: > > Hi Daniel, > > On Tue, 9 Feb 2021 at 02:36, Daniel Vetter <daniel@ffwll.ch> wrote: > > > > On Mon, Feb 8, 2021 at 9:51 PM John Stultz <john.stultz@linaro.org> wrote: > > > On Mon, Feb 8, 2021 at 2:08 AM Daniel Vetter <daniel@ffwll.ch> wrote: > > > > On Sat, Feb 06, 2021 at 05:47:48AM +0000, John Stultz wrote: > > > > > By default dma_buf_export() sets the exporter name to be > > > > > KBUILD_MODNAME. Unfortunately this may not be identical to the > > > > > string used as the heap name (ie: "system" vs "system_heap"). > > > > > > > > > > This can cause some minor confusion with tooling, and there is > > > > > the future potential where multiple heap types may be exported > > > > > by the same module (but would all have the same name). > > > > > > > > > > So to avoid all this, set the exporter exp_name to the heap name. > > > > > > > > > > Cc: Daniel Vetter <daniel@ffwll.ch> > > > > > Cc: Sumit Semwal <sumit.semwal@linaro.org> > > > > > Cc: Liam Mark <lmark@codeaurora.org> > > > > > Cc: Chris Goldsworthy <cgoldswo@codeaurora.org> > > > > > Cc: Laura Abbott <labbott@kernel.org> > > > > > Cc: Brian Starkey <Brian.Starkey@arm.com> > > > > > Cc: Hridya Valsaraju <hridya@google.com> > > > > > Cc: Suren Baghdasaryan <surenb@google.com> > > > > > Cc: Sandeep Patil <sspatil@google.com> > > > > > Cc: Daniel Mentz <danielmentz@google.com> > > > > > Cc: Ørjan Eide <orjan.eide@arm.com> > > > > > Cc: Robin Murphy <robin.murphy@arm.com> > > > > > Cc: Ezequiel Garcia <ezequiel@collabora.com> > > > > > Cc: Simon Ser <contact@emersion.fr> > > > > > Cc: James Jones <jajones@nvidia.com> > > > > > Cc: linux-media@vger.kernel.org > > > > > Cc: dri-devel@lists.freedesktop.org > > > > > Signed-off-by: John Stultz <john.stultz@linaro.org> > > > > > > > > Looks reasonable to me. > > > > > > > > I guess the main worry is "does this mean heap names become uapi", in > > > > which case I'm maybe not so sure anymore how this will tie into the > > > > overall gpu memory accounting story. > > > > > > > > Since for dma-buf heaps one name per buffer is perfectly fine, since > > > > dma-buf heaps aren't very dynamic. But on discrete gpu drivers buffers > > > > move, so baking in the assumption that "exporter name = resource usage for > > > > this buffer" is broken. > > > > > > I suspect I'm missing a subtlety in what you're describing. My sense > > > of the exporter name doesn't account for a buffer's usage, it just > > > describes what code allocated it and implicitly which dmabuf_ops > > > handles it. Maybe could you give a more specific example of what > > > you're hoping to avoid? > > > > Just paranoia really - on the linux side where we allocate most > > buffers (even shared ones) with the driver, that allocator info isn't > > that meaningful, it really just tells you which code > > allocated/exported that dma-buf. > > > > But on Android, where all shared buffers come from specific heaps, it > > is rather meaningful information. So I wondered whether e.g. the > > android dmabuf debug tool uses that to collect per-heap stats, but > > sounds like no right now. Plus with the chat we've had I think we have > > a long-term plan for how to expose that information properly. > > > > > To me this patch is mostly just a consistency/least-surprise thing, so > > > the heaps exporter name matches the string used for the heap's chardev > > > device (the interface used to allocate it) in output like > > > debugfs/dma_buf/bufinfo. > > > > Yeah for debug this makes sense. a-b: me if you want that somewhere on > > the patches. > > Great that this got sorted; I'll apply both the patches of this series > to drm-misc-next, with your a-b. Before you do, let me spin a v2 as I got some minor tweaks needed (using const char*) to fix the kbuild bot errors. thanks -john
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index afd22c9dbdcf..6c746ea67676 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -190,6 +190,19 @@ void *dma_heap_get_drvdata(struct dma_heap *heap) return heap->priv; } + +/** + * dma_heap_get_name() - get heap name + * @heap: DMA-Heap to retrieve private data for + * + * Returns: + * The char* for the heap name. + */ +char *dma_heap_get_name(struct dma_heap *heap) +{ + return heap->name; +} + struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) { struct dma_heap *heap, *h, *err_ret; diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 454e354d1ffb..b91778291fb1 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -50,6 +50,15 @@ struct dma_heap_export_info { */ void *dma_heap_get_drvdata(struct dma_heap *heap); +/** + * dma_heap_get_name() - get heap name + * @heap: DMA-Heap to retrieve private data for + * + * Returns: + * The char* for the heap name. + */ +char *dma_heap_get_name(struct dma_heap *heap); + /** * dma_heap_add - adds a heap to dmabuf heaps * @exp_info: information needed to register this heap
It can be useful to access the name for the heap, so provide an accessor to do so. Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Liam Mark <lmark@codeaurora.org> Cc: Chris Goldsworthy <cgoldswo@codeaurora.org> Cc: Laura Abbott <labbott@kernel.org> Cc: Brian Starkey <Brian.Starkey@arm.com> Cc: Hridya Valsaraju <hridya@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Sandeep Patil <sspatil@google.com> Cc: Daniel Mentz <danielmentz@google.com> Cc: Ørjan Eide <orjan.eide@arm.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Ezequiel Garcia <ezequiel@collabora.com> Cc: Simon Ser <contact@emersion.fr> Cc: James Jones <jajones@nvidia.com> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz <john.stultz@linaro.org> --- drivers/dma-buf/dma-heap.c | 13 +++++++++++++ include/linux/dma-heap.h | 9 +++++++++ 2 files changed, 22 insertions(+)