Memory Management in TIZEN - Samsung SW Platform Team
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Memory Management in TIZEN - Samsung Software Platform Team (Samsung Software R&D Center)
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Memory Management in TIZEN - Samsung SW Platform Team
- 1. Memory Management in Tizen SW Platform Team, SW R&D Center
- 2. tizen.org2 Contents • Tizen Kernel Overview • Memory Management in Tizen Kernel • Memory Size Optimization
- 4. tizen.org4 Tizen Kernel Overview Kernel Kernel OAL (OEM Adaptation Layer) Telephony Plug-ins GStreamer Plug-ins Sensor Plug-ins System Plug-ins OpenGL ES/EGL Graphics Driver Graphics Memory Management IOMMU DMA BUF Multimedia Power Management CPUfre q Devf req Ther mal … DRM Link1 Link2 V4L2 Storage Block Layer MMC/Flash Input, Sensor, … Peripheral CMA OpenGL ES 1.0/2.0 X11 GStreamerEFL . . . Multimedia FW Telephony FW . . .Sensor FW System FW . . . More at http://source.tizen.org/documentation/porting-guide Core DRM Link1: http:// elinux.org/images/7/71/Elce11_dae.pdf DRM Link2: http://download.tizen.org/misc/media/conference2012/wednesday/ballroom-c/2012-05-09-1330-1410- the_drm_(direct_rendering_manager)_of_tizen_kernel.pdf
- 5. tizen.org5 Tizen Kernel Overview Kernel Kernel OAL (OEM Adaptation Layer) Telephony Plug-ins GStreamer Plug-ins Sensor Plug-ins System Plug-ins OpenGL ES/EGL Graphics Driver Graphics Memory Management IOMM U DMA BUF Multimedia Power Management CPUfre q Devf req Ther mal …DRM Link1 Link2 V4L2 Storage Block Layer MMC/Flash Input, Sensor, … Peripheral CM A OpenGL ES 1.0/2.0 X11 GStreamerEFL . . . Multimedia FW Telephony FW . . .Sensor FW System FW . . . More at http://source.tizen.org/documentation/porting-guide Core Service Layer DRM Link1: http:// elinux.org/images/7/71/Elce11_dae.pdf DRM Link2: http://download.tizen.org/misc/media/conference2012/wednesday/ballroom-c/2012-05-09-1330-1410- the_drm_(direct_rendering_manager)_of_tizen_kernel.pdf • Memory Management in Tizen – Coupled with Graphics & Multimedia devices. • Graphics & Multimedia devices = DMA devices with HUGE buffers
- 6. tizen.org6 Tizen Kernel Overview Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension UMM Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc DMABUF
- 7. tizen.org7 Contents • Tizen Kernel Overview • Memory Management in Tizen Kernel – To Run Tizen OS. • Basic Memory Management Components • Buffer Sharing (UMM/DMABUF) • Buffer Allocation (UMM/DMAAPI) • Buffer Synchronization • Memory Size Optimization
- 8. tizen.org8 Tizen Kernel MM, Graphics (DRM) Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension UMM Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc DMABUF
- 9. tizen.org9 Graphics: DRM/GEM (Graphics Execution Manager) drm_fb_helperdrm_mode_config Linux DRM Common Framework GEM drm_framebuffer fb_infoCrtc Connector Encoder GEM Allocator Plane Common Specific drm_framebufferCrtc Connector Encoder Plane
- 10. tizen.org10 Graphics: DRM/GEM (Graphics Execution Manager) drm_fb_helperdrm_mode_config Linux DRM Common Framework GEM drm_framebuffer fb_infoCrtc Connector Encoder GEM Allocator Plane Common Specific drm_framebufferCrtc Connector Encoder Plane Graphics Execution Manager • Framework developed by Intel • To manage graphics memory • Framework for buffer management. • Allocation and sharing.
- 11. tizen.org11 Graphics: DRM/GEM Allocation • GEM Allocation steps @ Tizen (Generic) 1. DRM_IOCTL_MODE_CREATE_DUMB • Create GEM object(global) & user GEM handle(per process) • dumb_create() of struct drm_driver • No physical memory allocated. 2. DRM_IOCTL_MODE_MAP_DUMB • Create fake mmap offset of a gem object and relay the object to user • A hash key of the gem object. • dumb_map_offset() of struct drm_driver 3. MMAP • Request mmap based on the hash key as the offset • Create user address space • Setup cache attribute. • Not mapped to physical memory, yet
- 12. tizen.org12 Graphics: DRM/GEM Allocation • GEM Allocation steps @ Tizen (Generic) 4. On-demand Paging – Implement & Register a fault handler that • With a page fault, allocate a page and map the page. – vma->vm_ops->fault = xxx_drm_gem_fault 5. Use! 6. DRM_IOCTL_MODE_DESTROY_DUMB – Remove GEM handle & object – Free memory – Implement dumb_destroy() of struct drm_driver
- 13. tizen.org13 Graphics: DRM/GEM Allocation • GEM Allocation steps @ Tizen (Exynos Only) 1. DRM_IOCTL_EXYNOS_GEM_CREATE • Only use user-desired size and buffer types. • Create gem object(global) & user gem handle(per process) • physical memory allocated. 2. DRM_IOCTL_EXYNOS_GEM_MMAP • Create user address space • Map the user address space to physical memory • LIBDRM of Exynos uses these APIs, not the generic.
- 14. tizen.org14 Graphics: DRM/GEM Sharing • GEM Sharing @ Tizen • DRM_IOCTL_GEM_FLINK – “I will share this GEM to others.” – Create GEM object name for the given GEM handle • Global key vaue for sharing • DRM_IOCTL_GEM_OPEN – “I want to use the shared GEM.” – Create GEM handle based on the given GEM object name • DRM_IOCTL_GEM_CLOSE • You don’t need to implement. It’s already there with DRM. GEM Create GEM FLINK GEM OPEN gem handle gem object name gem handle Process 1 Process 2
- 15. tizen.org15 Tizen Kernel MM, Multimedia (V4L2/VB2) Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension UMM Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc DMABUF
- 16. tizen.org16 Multimedia: V4L2/VB2 • Tizen recommends to use V4L2 at Tizen kernel for Multimedia devices • Video input (codec & camera) & Radio • However, as long as the kernel has: – Gstreamer/OpenMAX plugins – A method to share with other F/W via DMABUF of UMM, • Tizen multimedia works. • If V4L2/VB2 is used, things get easier.
- 17. tizen.org17 Tizen Kernel MM, OpenGL/G3D-GPU Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension UMM Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc DMABUF
- 18. tizen.org18 OpenGL / G3D-GPU • Most ARM SoC GPUs (MALI, SGX, …) use their own memory manager • E.g., Exynos4412/4210 Tizen Reference Kernel has Mali w/ UMP. – Mali DDK modified to be compatible with UMM-DMABUF. • If GPU drivers use DRM, it would be great. • (and make them GPL)
- 19. tizen.org19 Contents • Tizen Kernel Overview • Memory Management in Tizen Kernel – To Run Tizen OS. • Basic Memory Management Components • Buffer Sharing (UMM/DMABUF) • Buffer Allocation (UMM/DMAAPI) • Buffer Synchronization • Memory Size Optimization
- 20. tizen.org20 NEED FOR SOMETHING, A Scenario Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc Camera fetches a video stream This scenario is simplified for presentation. Not an actual example of Tizen
- 21. tizen.org21 NEED FOR SOMETHING, A Scenario Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc Camera fetches a video stream Draws its own images This scenario is simplified for presentation. Not an actual example of Tizen
- 22. tizen.org22 NEED FOR SOMETHING, A Scenario Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc Camera fetches a video stream Draws its own images GPU Merges the two / Puts the merged image This scenario is simplified for presentation. Not an actual example of Tizen
- 23. tizen.org23 NEED FOR SOMETHING, A Scenario Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc Camera fetches a video stream Draws its own images DRM-FIMD(display) Output This scenario is simplified for presentation. Not an actual example of Tizen GPU Merges the two / Puts the merged image
- 24. tizen.org24 NEED FOR SOMETHING, A Scenario Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc Camera fetches a video stream Draws its own images DRM-FIMD(display) Output At a VB2 buffer At a GEM buffer GEM buffer This scenario is simplified for presentation. Not an actual example of Tizen GPU Merges the two / Puts the merged image From GEM + VB2 into its own (e.g., UMP)
- 25. tizen.org25 Tizen Kernel MM, UMM Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension UMM Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc DMABUF A mechanism to share between DRM, V4L2, and others w/o memcpy
- 26. tizen.org26 Tizen Kernel MM, UMM Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension UMM Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc DMABUF Requirement from Tizen platform and hardware • Different Memory Managers: GEM, VB2, GPU-adhoc, … • Share buffers • w/o memcpy • From and to users • Never expose directly to users (e.g., physical address) UMM DMABUF!
- 27. tizen.org27 Tizen Kernel Memory Management Unified Memory Management (UMM) • Introduced by Jesse Barker, 2011 • Includes – DMABUF (sharing buffer) – DMA Mapping API for Allocation. – CMA (Contiguous Memory Allocator) IOMMU (MMU for I/O devs)
- 28. tizen.org28 Tizen Kernel MM, UMM DMA Buffer Sharing: DMABUF • Export – GEM/VB2/… object DMABUF • Import – DMABUF GEM/VB2/… object • Userspace sees DMABUF as a File Descriptor
- 29. tizen.org29 DMA Buffer Sharing: DMABUF, Example Camera Display X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 30. tizen.org30 DMA Buffer Sharing: DMABUF, Example Conceptual Data Flow X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 31. tizen.org31 DMABUF Usage Example 1/4 Camera App 1) Request V4L2 camera buffer (U) 2) Allocate CMA buffer (K) 3) Request a camera frame at the V4L2 buffer (U) 4) Store the camera frame & Notify user (K) 5) Request DMABUF export for the V4L2 camera buffer (U) 6) dma_buf_exporter() (K) - Create DMABUF from V4L2 buffer 7) dma_buf_fd() (K) - Provide FD of the DMABUF to user X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 32. tizen.org32 DMABUF Usage Example 1/4 Camera App 1) Request V4L2 camera buffer (U) 2) Allocate CMA buffer (K) 3) Request a camera frame at the V4L2 buffer (U) 4) Store the camera frame & Notify user (K) 5) Request DMABUF export for the V4L2 camera buffer (U) 6) dma_buf_exporter() (K) - Create DMABUF from V4L2 buffer 7) dma_buf_fd() (K) - Provide FD of the DMABUF to user X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 33. tizen.org33 DMABUF Usage Example 1/4 Camera App 1) Request V4L2 camera buffer (U) 2) Allocate CMA buffer (K) 3) Request a camera frame at the V4L2 buffer (U) 4) Store the camera frame & Notify user (K) 5) Request DMABUF export for the V4L2 camera buffer (U) 6) dma_buf_exporter() (K) - Create DMABUF from V4L2 buffer 7) dma_buf_fd() (K) - Provide FD of the DMABUF to user X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 34. tizen.org34 DMABUF Usage Example 2/4 Camera App 8) Request FD->GEM conversion (U) 9) dma_buf_get(fd) (K) - Get DMABUF from FD 10)dma_buf_attach(dma-buf) / dma_buf_map_attachment() (K) - Get Buffer from DMABUF 11) Import as GEM, send user (K) 12) Request GEM object name (U) 13) Return GEM object name (K) 14) Send GEM object name to X (U) X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 35. tizen.org35 DMABUF Usage Example 2/4 Camera App 8) Request FD->GEM conversion (U) 9) dma_buf_get(fd) (K) - Get DMABUF from FD 10) dma_buf_attach(dma-buf) / dma_buf_map_attachment() (K) - Get Buffer from DMABUF 11) Import as GEM, send user (K) 12) Request GEM object name (U) 13) Return GEM object name (K) 14) Send GEM object name to X (U) X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 36. tizen.org36 DMABUF Usage Example 3/4 X server 15) Convert given GEM object name to GEM. Display its content. (U & K) X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 37. tizen.org37 DMABUF Usage Example 3/4 X server 15) Convert given GEM object name to GEM. Display its content. (U & K) X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 38. tizen.org38 DMABUF Usage Example 4/4 Close after usage 1) “Free” the GEM object (U) 2) Remove reference from the DMABUF (K) 3) Close(DMABUF-FD) at cam app (U) 4) (No more reference to DMABUF) Release callback executed (K) X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 39. tizen.org39 DMABUF Usage Example 4/4 Close after usage 1) “Free” the GEM object (U) 2) Remove reference from the DMABUF 3) Close(DMABUF-FD) at cam app (U) 4) (No more reference to DMABUF) Release callback executed (K) X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 40. tizen.org40 DMABUF Usage Example 4/4 Close after usage 1) “Free” the GEM object (U) 2) Remove reference from the DMABUF 3) Close(DMABUF-FD) at cam app (U) 4) (No more reference to DMABUF) Release callback executed (K) X server Video encoder Xvsink Camera src User space Kernel space DRM KMS GEM Codec CameraV4L2 V4L2 struct dma_buf Display Codec Camera Memory Camera App FD HW
- 41. tizen.org41 Sorry, Back to DRM/GEM… • DMABUF Import / Export needs to be added • DRM_IOCTL_PRIME_HANDLE_TO_FD • Export gem handle into dmabuf fd • DRM_IOCTL_PRIME_FD_TO_HANDLE • Import dmabuf fd into gem handle
- 42. tizen.org42 Contents • Tizen Kernel Overview • Memory Management in Tizen Kernel – To Run Tizen OS. • Basic Memory Management Components • Buffer Sharing (UMM/DMABUF) • Buffer Allocation (UMM/DMAAPI) • Buffer Synchronization • Memory Size Optimization
- 43. tizen.org43 Tizen Kernel Memory Management Unified Memory Management (UMM) • Introduced by Jesse Barker, 2011 • Includes – DMABUF (sharing buffer) – DMA Mapping API for Allocation. – CMA (Contiguous Memory Allocator) IOMMU (MMU for I/O devs)
- 44. tizen.org44 Tizen Kernel MM, UMM DMA Mapping API @ Tizen Reference DRM / GEM DMA Mapping Framework IOMMUBuddyCMA IOMMU Common Driver System Memory V4L2 / VB2 1 2 1: “Exynos-DRM” provides unified device address space for all DRM devices 2: Each V4L2 device has its own device address space 2 2
- 45. tizen.org45 Contents • Tizen Kernel Overview • Memory Management in Tizen Kernel – To Run Tizen OS. • Basic Memory Management Components • Buffer Sharing (UMM/DMABUF) • Buffer Allocation (UMM/DMAAPI) • Buffer Synchronization • Memory Size Optimization
- 46. tizen.org46 Tizen Kernel Memory Management We Still Have A HUGE Problem!
- 47. tizen.org47 Tizen Kernel MM, Buffer Sync. Kernel / Device Drivers (BSP) Kernel / Core & Subsystem X Server DRM Framework GEM Display HDMI Virtual Display Post Processor G2D EFL Evas 2D GPU backend X Video Drivers Userptr NEON 2D GPU backend PIXMAN EXA V4L2 VB2 Codec Camera GStreamer OpenMAX Libdrm XV Extension UMM Open GL Multimedia FW XvImageSink Core External Library Core Framework OEM Adaptation Kernel Kernel GPU DDK (G3D) Radio * Images from MS Office clipart and Samsung Gstreamer- CameraSrc DMABUF Synchronization?
- 48. tizen.org48 Tizen Kernel MM, Buffer Sync. What’s the problem? BUS DRAMDRAMDRAM CPU GPU Simple Usage Scenario 1. CPU writes to buffer1. 2. CPU tells GPU to do something on buffer1. 3. GPU does something on buffer1. 4. GPU finishes. 5. CPU reads the buffer1
- 49. tizen.org49 Tizen Kernel MM, Buffer Sync. What’s the problem? BUS DRAMDRAMDRAM CPU GPU Simple Usage Scenario 1. CPU writes to buffer1. 2. CPU tells GPU to do something on buffer1. 3. GPU does something on buffer1. 4. GPU finishes. 5. CPU reads the buffer1
- 50. tizen.org50 Tizen Kernel MM, Buffer Sync. What’s the problem? BUS DRAMDRAMDRAM CPU GPU Simple Usage Scenario 1. CPU writes to buffer1. 2. CPU tells GPU to do something on buffer1. 3. GPU does something on buffer1. 4. GPU finishes. 5. CPU reads the buffer1
- 51. tizen.org51 Tizen Kernel MM, Buffer Sync. What’s the problem? BUS DRAMDRAMDRAM CPU GPU Simple Usage Scenario 1. CPU writes to buffer1. 2. CPU tells GPU to do something on buffer1. 3. GPU does something on buffer1. 4. GPU finishes. 5. CPU reads the buffer1
- 52. tizen.org52 Tizen Kernel MM, Buffer Sync. What’s the problem? BUS DRAMDRAMDRAM CPU GPU Simple Usage Scenario 1. CPU writes to buffer1. 2. CPU tells GPU to do something on buffer1. 3. GPU does something on buffer1. 4. GPU finishes. 5. CPU reads the buffer1
- 53. tizen.org53 Tizen Kernel MM, Buffer Sync. What’s the problem? Simple Usage Scenario 1. CPU writes to buffer1. 2. CPU tells GPU to do something on buffer1. 3. GPU does something on buffer1. 4. GPU finishes. 5. CPU reads the buffer1 How to ensure CPU won’t use buffer 1 until step 4? (esp., a user process)
- 54. tizen.org54 Tizen Kernel MM, Buffer Sync. What’s the problem? BUS DRAMDRAMDRAM CPU, Thread1 GPU • What if there are two threads using GPU? – And if the two look at the same buffer? • Not even aware of it? CPU, Thread2
- 55. tizen.org55 Tizen Kernel MM, Buffer Sync. What’s the problem? BUS DRAMDRAMDRAM CPU, Thread1 GPU • What if the two DMA devices (GPU, FIMC) share buffer? – But hard to know it at drivers or user threads. – FIMC never knows when GPU finishes – FIMC never knows when Threads1 stops using “buffer1” – Threads2 never know when GPU stops using “buffer1” CPU, Thread2 FIMC-IPP (Image Post Processing)
- 56. tizen.org56 Tizen Kernel Memory Management Buffer Synchronization • TGL (Tizen Global Lock) @ Tizen 2.0 – … Let userspace handle the issue … – Kernel patch required. • Sync Framework (Google) – Jun, 2012. Resources w/o DMABUF (similar with TGL) • KDS (Kernel Dependency System, ARM) – May 2012 / DMABUF-compatible • DMA Fence Framework (Canonical/TI) – Aug 2012 / DMABUF-compatible – Work-In-Progress
- 57. tizen.org57 Contents • Tizen Kernel Overview • Memory Management in Tizen Kernel • Memory Size Optimization – To Run w/ More Devices
- 58. tizen.org58 Memory Size Optimization: Challenge • A device with 512MB RAM • Graphics/Multimedia devices want 400MB reserved – No IOMMU. • The userspace wants to run a web browser and HTML5 app! •REALLY POSSIBLE?
- 59. tizen.org59 Memory Size Optimization: Challenge • A device with 512MB RAM • Graphics/Multimedia devices want 400MB reserved – No IOMMU • The userspace wants to run a web browser and HTML5 app! •REALLY POSSIBLE? •WHY NOT?
- 60. tizen.org60 Minimize H/W Reserved Memory CMA (Contiguous Memory Allocator) • Camera wants to reserve 400MB. – No IOMMU: too primitive to use paging. • You don’t use cameras while web browsing. – Free the 400MB reserved to camera, let userspace use it. • CMA can do.
- 61. tizen.org61 Minimize H/W Reserved Memory • (Obsolete/Low-cost) ARM SoC’s DMA devices – No IOMMU – Use physically continuous memory chunk. • No paging • Potentially, a lot of memory is wasted. BUS CPU MMU L2 Cache DRAM Controller DRAMDRAMDRAM CPUCPU GPU
- 62. tizen.org62 Minimize H/W Reserved Memory IOMMU • (Modern/Mid-High-cost) ARM SoC’s DMA devices – IOMMU for DMA devices! – Use paging! • Dynamically allocate & free BUS CPU MMU L2 Cache DRAM Controller DRAMDRAMDRAM CPUCPU GPU IOMMU
- 63. tizen.org63 Minimize H/W Reserved Memory IOMMU • Exynos4210/4412-based Tizen mobile device – Achieved near-zero reserved memory. – At the “menuscreen”, only around ~40MB allocated for display and GPU. – Unfortunately, not included in the Tizen reference kernel. • But easily supported by Vanilla kernel for Tizen reference boards
- 64. tizen.org64 Minimize H/W Reserved Memory Results with 1GB RAM Device -sh-4.1# free total used free shared buffers cached Mem: 1029428 302020 727408 0 16164 133084 -/+ buffers/cache: 152772 876656 Swap: 0 0 0 -sh-4.1# uname -a Linux localhost 3.8.3-00841-gc1981b1 #34 SMP PREEMPT Wed Apr 10 10:24:04 KST 2013 armv7l GNU/Linux Mostly available to kernel (1005.3 of 1024MB) Even with Tizen loaded, mostly free to users (856MB of 1GB)
- 65. tizen.org65 Memory Size Optimization: Still Hungry? • Further optimization required for low-budget devices – Running full features with 512MB? – Or even < 512MB? • What about multi-tasking or “background apps”?
- 66. tizen.org66 Memory Size Optimization: SWAP • Swap – zRAM • Used in some Samsung mobile devices successfully – Or even swap-to-flash?
- 67. tizen.org67 Memory Size Optimization: Multitasking / Background Apps • Limit multitasking & background-app support • Pseudo multitasking by freezing background apps
- 68. Thank you!