On Mon, Feb 1, 2021 at 10:37 AM Daniel Vetter daniel@ffwll.ch wrote:
On Thu, Jan 28, 2021 at 1:03 PM Sumit Semwal sumit.semwal@linaro.org wrote:
On Thu, 28 Jan 2021 at 17:23, Christian König ckoenig.leichtzumerken@gmail.com wrote:
Am 28.01.21 um 12:00 schrieb Sumit Semwal:
Hi Hridya,
On Wed, 27 Jan 2021 at 17:36, Greg KH gregkh@linuxfoundation.org wrote:
On Tue, Jan 26, 2021 at 12:42:36PM -0800, Hridya Valsaraju wrote:
This patch allows statistics to be enabled for each DMA-BUF in sysfs by enabling the config CONFIG_DMABUF_SYSFS_STATS.
The following stats will be exposed by the interface:
/sys/kernel/dmabuf/buffers/<inode_number>/exporter_name /sys/kernel/dmabuf/buffers/<inode_number>/size /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/device /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/map_counter
The inode_number is unique for each DMA-BUF and was added earlier [1] in order to allow userspace to track DMA-BUF usage across different processes.
Currently, this information is exposed in /sys/kernel/debug/dma_buf/bufinfo. However, since debugfs is considered unsafe to be mounted in production, it is being duplicated in sysfs.
This information will be used to derive DMA-BUF per-exporter stats and per-device usage stats for Android Bug reports. The corresponding userspace changes can be found at [2]. Telemetry tools will also capture this information(along with other memory metrics) periodically as well as on important events like a foreground app kill (which might have been triggered by Low Memory Killer). It will also contribute to provide a snapshot of the system memory usage on other events such as OOM kills and Application Not Responding events.
A shell script that can be run on a classic Linux environment to read out the DMA-BUF statistics can be found at [3](suggested by John Stultz).
The patch contains the following improvements over the previous version:
- Each attachment is represented by its own directory to allow creating
a symlink to the importing device and to also provide room for future expansion. 2) The number of distinct mappings of each attachment is exposed in a separate file. 3) The per-buffer statistics are now in /sys/kernel/dmabuf/buffers inorder to make the interface expandable in future.
All of the improvements above are based on suggestions/feedback from Daniel Vetter and Christian König.
Signed-off-by: Hridya Valsaraju hridya@google.com Reported-by: kernel test robot lkp@intel.com
Thanks for the patch!
Christian: If you're satisfied with the explanation around not directly embedding kobjects into the dma_buf and dma_buf_attachment structs, then with Greg's r-b from sysfs PoV, I think we can merge it. Please let me know if you feel otherwise!
From the technical side it looks clean to me, feel free to add my acked-by while pushing.
But I would at least try to convince Daniel on the design. At least some of his concerns seems to be valid and keep in mind that we need to support this interface forever.
Naturally.
Since he didn't comment over Hridya's last clarification about the tracepoints to track total GPU memory allocations being orthogonal to this series, I assumed he agreed with it.
The tracepoint being orthogonal didn't really look convincing to me, since I do expect we'll need that at a much more generic level, at allocators. Whether that's dma-buf heaps or in drm or wherever. And we probably also need that to somehow align with cgroups accounting.
But I guess for this it should be easy to extend however we see fit, so retrofitting allocator sources and anything else we want/need for the overall gpu memory account shouldn't be a problem. Also, it's first, so the proof for showing it all works together is more on the tracepoints :-)
Daniel, do you still have objections around adding this patch in?
Needs docs (especially the uapi I think would be useful to document), igt tests, that kind of stuff still I think? It's meant to be generic uapi across drivers, generally we're a pile stricter for that (and yes dma-buf heaps I think didn't do all that, so maybe there's an argument for doing this a bit more sloppy or at least "the testsuite is somewhere else").
Thank you for taking another look Daniel!
I will try adding an IGT test for the sysfs files. Other than the documentation in Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers(included in the patch), is there another place you would like to see the documentation copied to?
Regards, Hridya
But I think it would be good to have this all done. -Daniel
Regards, Christian.
Best, Sumit.
Changes in v3: Fix a warning reported by the kernel test robot.
Changes in v2: -Move statistics to /sys/kernel/dmabuf/buffers in oder to allow addition of other DMA-BUF-related sysfs stats in future. Based on feedback from Daniel Vetter. -Each attachment has its own directory to represent attaching devices as symlinks and to introduce map_count as a separate file. Based on feedback from Daniel Vetter and Christian König. Thank you both! -Commit messages updated to point to userspace code in AOSP that will read the DMA-BUF sysfs stats.
.../ABI/testing/sysfs-kernel-dmabuf-buffers | 52 ++++ drivers/dma-buf/Kconfig | 11 + drivers/dma-buf/Makefile | 1 + drivers/dma-buf/dma-buf-sysfs-stats.c | 285 ++++++++++++++++++ drivers/dma-buf/dma-buf-sysfs-stats.h | 62 ++++ drivers/dma-buf/dma-buf.c | 37 +++ include/linux/dma-buf.h | 20 ++ 7 files changed, 468 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers create mode 100644 drivers/dma-buf/dma-buf-sysfs-stats.c create mode 100644 drivers/dma-buf/dma-buf-sysfs-stats.h
I don't know the dma-buf code at all, but from a sysfs/kobject point of view, this patch looks good to me:
Reviewed-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
Best, Sumit. _______________________________________________ Linaro-mm-sig mailing list Linaro-mm-sig@lists.linaro.org https://lists.linaro.org/mailman/listinfo/linaro-mm-sig
-- Thanks and regards,
Sumit Semwal Linaro Consumer Group - Tech Lead Linaro.org │ Open source software for ARM SoCs _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch