• Show log

    Commit

  • Hash : 2fae9482
    Author : Charlie Lao
    Date : 2022-05-02T11:05:36

    Vulkan: Use heuristic to decide how many empty buffers to keep
    
    Instead of rely on static information (16 max empty buffers and not been
    used for a given period of time), this CL keeps track of how many new
    buffers are needed (either reused from empty buffer list or allocated
    new) since last prune. We use this heuristic information to decide how
    many empty buffers to keep around and trim the excessive empty buffers.
    
    Combined with the next few CLs, on pixel6 I am seeing 11.7M reduction
    with vsync_angry_birds_2_1500. The memory_max minus memory_median
    reduced from 49M to 38M.
    
    Bug: b/230538246
    Change-Id: I51da745afe4bfdbff0ba165418531803bdce681b
    Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3622264
    Commit-Queue: Charlie Lao <cclao@google.com>
    Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com>
    Reviewed-by: Jamie Madill <jmadill@chromium.org>
    

  • Properties

  • Git HTTP https://git.kmx.io/kc3-lang/angle.git
    Git SSH git@git.kmx.io:kc3-lang/angle.git
    Public access ? public
    Description

    A conformant OpenGL ES implementation for Windows, Mac, Linux, iOS and Android.

    Homepage

    Github

    Users
    kc3_lang_org thodg_w www_kmx_io thodg_l thodg thodg_m
    Tags

  • README.md

  • ANGLE: Vulkan Back-end

    ANGLE’s Vulkan back-end implementation lives in this folder.

    Vulkan is an explicit graphics API. It has a lot in common with other explicit APIs such as Microsoft’s D3D12 and Apple’s Metal. Compared to APIs like OpenGL or D3D11 explicit APIs can offer a number of significant benefits:

    • Lower API call CPU overhead.
    • A smaller API surface with more direct hardware control.
    • Better support for multi-core programming.
    • Vulkan in particular has open-source tooling and tests.

    Back-end Design

    The RendererVk class represents an EGLDisplay. RendererVk owns shared global resources like the VkDevice, VkQueue, the Vulkan format tables and internal Vulkan shaders. The ContextVk class implements the back-end of a front-end OpenGL Context. ContextVk processes state changes and handles action commands like glDrawArrays and glDrawElements.

    Command recording

    The back-end records commands into command buffers via the following ContextVk APIs:

    • beginNewRenderPass: Writes out (aka flushes) prior pending commands into a primary command buffer, then starts a new render pass. Returns a secondary command buffer inside a render pass instance.
    • getOutsideRenderPassCommandBuffer: May flush prior command buffers and close the render pass if necessary, in addition to issuing the appropriate barriers. Returns a secondary command buffer outside a render pass instance.
    • getStartedRenderPassCommands: Returns a reference to the currently open render pass’ commands buffer.

    The back-end (mostly) records Image and Buffer barriers through additional CommandBufferAccess APIs, the result of which is passed to getOutsideRenderPassCommandBuffer. Note that the barriers are not actually recorded until getOutsideRenderPassCommandBuffer is called:

    • onBufferTransferRead and onBufferComputeShaderRead accumulate VkBuffer read barriers.
    • onBufferTransferWrite and onBufferComputeShaderWrite accumulate VkBuffer write barriers.
    • onBuffferSelfCopy is a special case for VkBuffer self copies. It behaves the same as write.
    • onImageTransferRead and onImageComputerShadeRead accumulate VkImage read barriers.
    • onImageTransferWrite and onImageComputerShadeWrite accumulate VkImage write barriers.
    • onImageRenderPassRead and onImageRenderPassWrite accumulate VkImage barriers inside a started RenderPass.

    After the back-end records commands to the primary buffer and we flush (e.g. on swap) or when we call ContextVk::finishToSerial, ANGLE submits the primary command buffer to a VkQueue.

    See the code for more details.

    Simple command recording example

    In this example we’ll be recording a buffer copy command:

        // Ensure that ANGLE sets proper read and write barriers for the Buffers.
        vk::CommandBufferAccess access;
        access.onBufferTransferWrite(dstBuffer);
        access.onBufferTransferRead(srcBuffer);
    
        // Get a pointer to a secondary command buffer for command recording.
        vk::OutsideRenderPassCommandBuffer *commandBuffer;
        ANGLE_TRY(contextVk->getOutsideRenderPassCommandBuffer(access, &commandBuffer));
    
        // Record the copy command into the secondary buffer. We're done!
        commandBuffer->copyBuffer(srcBuffer->getBuffer(), dstBuffer->getBuffer(), copyCount, copies);

    Additional Reading

    More implementation details can be found in the doc directory: