Quantcast
Jump to content

New Game Changing Vulkan Extensions for Mobile: Buffer Device Address


Recommended Posts

2021-07-06-01-banner.jpg

The Samsung Developers team works with many companies in the mobile and gaming ecosystems. We're excited to support our partner, Arm, as they bring timely and relevant content to developers looking to build games and high-performance experiences. This Vulkan Extensions series will help developers get the most out of the new and game-changing Vulkan extensions on Samsung mobile devices.

Android R is enabling a host of useful Vulkan extensions for mobile, with three being key 'game changers'. These are set to improve the state of graphics APIs for modern applications, enabling new use cases and changing how developers can design graphics renderers going forward. You can expect to see these features across a variety of Android smartphones, such as the new Samsung Galaxy S21, and existing Samsung Galaxy S models like the Samsung Galaxy S20. The first blog explored the first game changer extension for Vulkan – ‘Descriptor Indexing'. This blog explores the second game changer extension – ‘Buffer Device Address.’

VK_KHR_buffer_device_address

VK_KHR_buffer_device_address is a monumental extension that adds a unique feature to Vulkan that none of the competing graphics APIs support.

Pointer support is something that has always been limited in graphics APIs, for good reason. Pointers complicate a lot of things, especially for shader compilers. It is also near impossible to deal with plain pointers in legacy graphics APIs, which rely on implicit synchronization.

There are two key aspects to buffer_device_address (BDA). First, it is possible to query a GPU virtual address from a VkBuffer. This is a plain uint64_t. This address can be written anywhere you like, in uniform buffers, push constants, or storage buffers, to name a few.

The key aspect which makes this extension unique is that a SPIR-V shader can load an address from a buffer and treat it as a pointer to storage buffer memory immediately. Pointer casting, pointer arithmetic and all sorts of clever trickery can be done inside the shader. There are many use cases for this feature. Some are performance-related, and some are new use cases that have not been possible before.

Getting the GPU virtual address (VA)

There are some hoops to jump through here. First, when allocating VkDeviceMemory, we must flag that the memory supports BDA:

VkMemoryAllocateInfo info = {…};
VkMemoryAllocateFlagsInfo flags = {…};
flags.flags = VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_BIT_KHR;
vkAllocateMemory(device, &info, NULL, &memory);

Similarly, when creating a VkBuffer, we add the VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT_KHR usage flag. Once we have created a buffer, we can query the VA:

VkBufferDeviceAddressInfoKHR info = {…};
info.buffer = buffer;
VkDeviceSize va = vkGetBufferDeviceAddressKHR(device, &info);

From here, this 64-bit value can be placed in a buffer. You can of course offset this VA. Alignment is never an issue as shaders specify explicit alignment later.

A note on debugging

When using BDA, there are some extra features that drivers must support. Since a pointer does not necessarily exist when replaying an application capture in a debug tool, the driver must be able to guarantee that virtual addresses returned by the driver remain stable across runs. To that end, debug tools supply the expected VA and the driver allocates that VA range. Applications do not care that much about this, but it is important to note that even if you can use BDA, you might not be able to debug with it.

typedef struct VkPhysicalDeviceBufferDeviceAddressFeatures {
    VkStructureType  sType;
    void*                     pNext;
    VkBool32              bufferDeviceAddress;
    VkBool32              bufferDeviceAddressCaptureReplay;
    VkBool32              bufferDeviceAddressMultiDevice;
} VkPhysicalDeviceBufferDeviceAddressFeatures;

If bufferDeviceAddressCaptureReplay is supported, tools like RenderDoc can support BDA.

Using a pointer in a shader

In Vulkan GLSL, there is the GL_EXT_buffer_reference extension which allows us to declare a pointer type. A pointer like this can be placed in a buffer, or we can convert to and from integers:

#version 450
#extension GL_EXT_buffer_reference : require
#extension GL_EXT_buffer_reference_uvec2 : require
layout(local_size_x = 64) in;

 // These define pointer types.
layout(buffer_reference, std430, buffer_reference_align = 16) readonly buffer ReadVec4
{
    vec4 values[];
};

 layout(buffer_reference, std430, buffer_reference_align = 16) writeonly buffer WriteVec4
{
    vec4 values[];
};

 layout(buffer_reference, std430, buffer_reference_align = 4) readonly buffer UnalignedVec4
{
    vec4 value;
};

 layout(push_constant, std430) uniform Registers
{
     ReadVec4 src;
    WriteVec4 dst;
} registers;

Placing raw pointers in push constants avoids all indirection for getting to a buffer. If the driver allows it, the pointers can be placed directly in GPU registers before the shader begins executing.

Not all devices support 64-bit integers, but it is possible to cast uvec2 <-> pointer. Doing address computation like this is fine.

uvec2 uadd_64_32(uvec2 addr, uint offset)
{
    uint carry;
    addr.x = uaddCarry(addr.x, offset, carry);
    addr.y += carry;
    return addr;
}

void main()
{
    uint index = gl_GlobalInvocationID.x;
    registers.dst.values[index] = registers.src.values[index];
     uvec2 addr = uvec2(registers.src);
    addr = uadd_64_32(addr, 20 * index);

Cast a uvec2 to address and load a vec4 from it. This address is aligned to 4 bytes.

    registers.dst.values[index + 1024] = UnalignedVec4(addr).value;
}

Pointer or offsets?

Using raw pointers is not always the best idea. A natural use case you could consider for pointers is that you have tree structures or list structures in GPU memory. With pointers, you can jump around as much as you want, and even write new pointers to buffers. However, a pointer is 64-bit and a typical performance consideration is to use 32-bit offsets (or even 16-bit offsets) if possible. Using offsets is the way to go if you can guarantee that all buffers live inside a single VkBuffer. On the other hand, the pointer approach can access any VkBuffer at any time without having to use descriptors. Therein lies the key strength of BDA.

Extreme hackery: physical pointer as specialization constants

This is a life saver in certain situations where you are desperate to debug something without any available descriptor set.

A black magic hack is to place a BDA inside a specialization constant. This allows for accessing a pointer without using any descriptors. Do note that this breaks all forms of pipeline caching and is only suitable for debug code. Do not ship this kind of code. Perform this dark sorcery at your own risk:

#version 450
#extension GL_EXT_buffer_reference : require
#extension GL_EXT_buffer_reference_uvec2 : require
layout(local_size_x = 64) in;

layout(constant_id = 0) const uint DEBUG_ADDR_LO = 0;
layout(constant_id = 1) const uint DEBUG_ADDR_HI = 0;

layout(buffer_reference, std430, buffer_reference_align = 4) buffer DebugCounter
{
    uint value;
};

void main()
{
    DebugCounter counter = DebugCounter(uvec2(DEBUG_ADDR_LO, DEBUG_ADDR_HI));
    atomicAdd(counter.value, 1u);
}

Emitting SPIR-V with buffer_device_address

In SPIR-V, there are some things to note. BDA is an especially useful feature for layering other APIs due to its extreme flexibility in how we access memory. Therefore, generating BDA code yourself is a reasonable use case to assume as well.

Enables BDA in shaders.

_OpCapability PhysicalStorageBufferAddresses
OpExtension "SPV_KHR_physical_storage_buffer"_

The memory model is PhysicalStorageBuffer64 and not logical anymore.

_OpMemoryModel PhysicalStorageBuffer64 GLSL450_

The buffer reference types are declared basically just like SSBOs.

_OpDecorate %_runtimearr_v4float ArrayStride 16
OpMemberDecorate %ReadVec4 0 NonWritable
OpMemberDecorate %ReadVec4 0 Offset 0
OpDecorate %ReadVec4 Block
OpDecorate %_runtimearr_v4float_0 ArrayStride 16
OpMemberDecorate %WriteVec4 0 NonReadable
OpMemberDecorate %WriteVec4 0 Offset 0
OpDecorate %WriteVec4 Block
OpMemberDecorate %UnalignedVec4 0 NonWritable
OpMemberDecorate %UnalignedVec4 0 Offset 0
OpDecorate %UnalignedVec4 Block_

Declare a pointer to the blocks. PhysicalStorageBuffer is the storage class to use.

OpTypeForwardPointer %_ptr_PhysicalStorageBuffer_WriteVec4 PhysicalStorageBuffer
%_ptr_PhysicalStorageBuffer_ReadVec4 = OpTypePointer PhysicalStorageBuffer %ReadVec4
%_ptr_PhysicalStorageBuffer_WriteVec4 = OpTypePointer PhysicalStorageBuffer %WriteVec4
%_ptr_PhysicalStorageBuffer_UnalignedVec4 = OpTypePointer PhysicalStorageBuffer %UnalignedVec4

Load a physical pointer from PushConstant.

_%55 = OpAccessChain %_ptr_PushConstant__ptr_PhysicalStorageBuffer_WriteVec4 %registers %int_1    
%56 = OpLoad %_ptr_PhysicalStorageBuffer_WriteVec4 %55_

Access chain into it.

_%66 = OpAccessChain %_ptr_PhysicalStorageBuffer_v4float %56 %int_0 %40_

Aligned must be specified when dereferencing physical pointers. Pointers can have any arbitrary address and must be explicitly aligned, so the compiler knows what to do.

OpStore %66 %65 Aligned 16

For pointers, SPIR-V can bitcast between integers and pointers seamlessly, for example:

%61 = OpLoad %_ptr_PhysicalStorageBuffer_ReadVec4 %60
%70 = OpBitcast %v2uint %61

// Do math on %70
%86 = OpBitcast %_ptr_PhysicalStorageBuffer_UnalignedVec4 %some_address

Conclusion

We have already explored two key Vulkan extension game changers through this blog and the previous one. The third and final part of this game changer blog series will explore ‘Timeline Semaphores’ and how developers can use this new extension to improve the development experience and enhance their games.

Follow Up

Thanks to Hans-Kristian Arntzen and the team at Arm for bringing this great content to the Samsung Developers community. We hope you find this information about Vulkan extensions useful for developing your upcoming mobile games.

The Samsung Developers site has many resources for developers looking to build for and integrate with Samsung devices and services. Stay in touch with the latest news by creating a free account or by subscribing to our monthly newsletter. Visit the Marketing Resources page for information on promoting and distributing your apps and games. Finally, our developer forum is an excellent way to stay up-to-date on all things related to the Galaxy ecosystem.

View the full blog at its source

Link to post
Share on other sites


Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Similar Topics

    • By STF News
      Samsung Electronics today announced a new partnership with CJ ENM, Asia’s leading entertainment and media group behind the Oscar-winning film ‘Parasite’, to build a virtual production studio to spearhead the production of future video content. Combining its cutting-edge Micro LED technology with CJ ENM’s globally recognized content production of television series and films, Samsung is taking the next step in a new initiative to innovate in the rapidly expanding virtual production market.
       
      Through this partnership, Samsung will supply its state-of-the-art display technology, The Wall, to CJ ENM’s virtual studio, a part of its television and film production studio complex scheduled to open in Paju, Korea later this year. The custom virtual production volume studio will be the first in the world to leverage The Wall’s boundless LED technology, unlocking new possibilities for video content production operations and virtual production solutions. The main display will be installed in an oval shape with a diameter of 20 meters and a height of seven meters or more, creating a seemingly endless backdrop to capture content.
       

       
      “We are excited to collaborate with CJ ENM to build a virtual production studio featuring Samsung’s most cutting-edge display technologies,” said Jong-hee Han, President of Visual Display Business at Samsung Electronics. “With this partnership, Samsung is launching a new virtual production industry initiative with a commitment to deliver innovative products and solutions that offer the optimal environment for next-generation content production.”
       
      This virtual production studio will use LED displays and connected cameras to create virtual settings in real-time. This solution will save time and reduce image compositing and on-location production costs while helping filmmakers to see the camera on the live-action set in any direction.
       
      The Wall’s modular technology allows creators to design environments to their specific requirements, enabling a variety of installation options such as ceiling installation and convex or concave design, depending on the internal studio design.
       

       
      The 2021 model of The Wall (Model Name: IWA) with Micro LED technology enhances visual expression with ultra-deep blacks and wide viewing angles, giving filmmakers and content creators the ultimate canvas to fulfill their visions. The modular screens are ideal for studios thanks to their precise color expression, HDR10+ and cinema LED picture quality technology and optimized frame rates for production houses. A new molding process is also applied to the modular surfaces of The Wall to minimize any moiré patterns from forming, a nuisance typically associated with filming standard LED screens.
       
      The Wall’s massive screen measures over 1,000 inches, producing vibrant colors and details supporting up to 16K high-resolution1 content. Dedicated frame rates for studio production, a new addition to this year’s model, allows producers to run content at frame rates such as 23.976, 29.97 and 59.94Hz, ensuring seamless videos sync with the most widely used camera framerates. Frame Rate Sync technology further reduces screen disruptions for true-to-life accuracy. With thoughtful dust and contamination-resistant LED protective films, plus a variety of easy-to-use solutions, such as remote management and color adjustment, The Wall is built for convenient management in any environment.
       
      CJ ENM Virtual Studio Concept Visual
       
      Both companies expect this collaboration to improve content production possibilities while satisfying a variety of customers by reimagining content production for today’s fast-paced entertainment environment.
       
      “The strategic partnership with Samsung will allow CJ ENM to push forward the creation of a new powerhouse of the next-generation content,” said Ho-sung Kang, CJ ENM CEO. “While CJ ENM is investing $4.4 billion over the next five years in entertainment content, we are taking the lead in building a global No. 1 production studio to become a world leading entertainment company.”
       
       
      About CJ ENM
      CJ ENM is Asia’s leading entertainment and lifestyle company headquartered in Seoul, Korea. Since 1995, the company has engaged in a wide array of businesses across the industry spectrum including media content, music, film, performing arts, and animation, providing its top notch original content to various media platforms. CJ ENM has created, produced and distributed globally acclaimed contents including Cannes-winning film Parasite, Tony Award-winning musical Kinky Boots, record-breaking Korean box office hits Roaring Currents, Extreme Job, Ode to My Father, along with sought-after television series such as Crash Landing On You, Mr. Sunshine, Guardian: The Lonely and Great God, Grandpas over Flowers, I Can See Your Voice and more. To offer the best K-Culture experiences worldwide, CJ ENM presents KCON/KCON:TACT, the world’s largest K-culture convention & festival celebrating Hallyu and Mnet Asian Music Awards (MAMA), Asia’s biggest music awards. With regional offices in Asia, Europe and the U.S., CJ ENM currently employs over 3,600 people.
       
       
      1 16K resolution is only available for horizontal layouts with a 15,360 x 2,160-pixel arrangement.
      View the full article
    • By STF News
      We’re constantly working to make your web experience better and more secure. This month we’re introducing our latest Samsung Internet beta, 15.0, with a engine upgrade as well as new features and privacy protections.
      To start off with, 15.0 will be based on Chromium M90. This means developers will have new APIs to work with as well as the 9.0 version of the v8 JavaScript engine.
      Adding the search widget to your home screen: long-press the Samsung Internet icon and select “widgets.” You will then be prompted to Add the search widget to your device’s homescreen.
      We’re working to make your search experience more intuitive and easier. 15.0 introduces a search widget to better integrate your web searching experience (with your chosen search provider) right to your home screen so your home screen searches better integrate with the rest of your web usage. More updates on the search experience is coming soon.
      We’re also including some enhancements to user privacy with 15.0 — notably making our browser more resistant to fingerprinting by introducing some “noise” in the results from APIs that are commonly used by finger-printers. Fingerprinting is one technique that tracking networks use to correlate information about people even when they use secret browsing mode or tracking blockers such as the previous version of our Smart Anti-Tracking did so building in fingerprinting resistance should help Samsung Internet users maintain their chosen privacy settings.
      Our new “Back-Forward cache” feature will allow you to navigate pages more quickly. For frequently accessed web pages, this will bring cache hits from ~20% to around ~70%, and should greatly speed up browsing time (and reduce data usage) as you flick between pages.
      Back-Forward cache (“bfcache”) is an in-memory cache that stores a complete snapshot of a page (including the JavaScript heap) as the user is navigating away. With the entire page in memory, the browser can easily restore it if the user returns. More info on how bfcache works can be found in this web.dev article.
      We’ve enhanced bfcache for Samsung Internet by adding some further heuristics to determine whether the page should be restored or not.
      To make back-forward cache work better for your sites, remember to set the follow the instructions on web.dev about optimising your page for bfcache.
      Privacy is also about the ability to delete your data when you choose to. We’re making it more straightforward to delete your browsing data by providing you more information about what you’re deleting.
      Another way we’re safeguarding your privacy is by making it more straightforward to use Secret Mode (our private browsing mode). With 15.0, once you select Secret Mode, Samsung Internet will launch in Secret Mode by default even if terminated.
      Our new Beta is available on both the Galaxy and Play stores for download today!
      If you find any bugs or issues, please let us know at: [email protected]
      View the full blog at its source
    • By STF News
      Samsung Electronics today launched the 2021 model of its boundary-pushing modular display The Wall (Model Name: IWA) globally. With the new AI processing technology, upgraded 120Hz frame rates, and versatile installation options, this year’s The Wall once again reimagines display technology to give businesses boundless flexibility to showcase content.
       

       
      “Samsung is dedicated to creating the most innovative displays for those at the forefront of video creation and brand experiences,” said Hyesung Ha, Senior Vice President of Visual Display Business at Samsung Electronics. “The 2021 The Wall is our most immersive and versatile display yet, giving businesses complete control to create their dream environments.”
       
      A new Micro AI Processor instantly analyzes and optimizes every frame of the video to deliver the best picture quality possible. By using up to 16 different neural network models, each trained in AI upscaling and deep learning technology, the Micro AI Processor can optimize picture quality up to 8K resolution, enhancing contrast and removing noise.
       
      The Wall’s Black Seal Technology blankets the screen with perfect uniformity, creating a seamless canvas for purer black levels with enhanced depth delivering unparalleled contrast and immaculate detail. With 1,600 nits peak brightness, The Wall provides clear images that stand out even in bright room environments. Ultra Chroma technology produces narrower wavelengths that create RGB colors twice as pure1 and more accurate than conventional LEDs. Each LED is now up to 40% smaller,2 increasing the pure black space between pixels for enhanced color uniformity and higher picture contrast.
       

       
      This year’s model is easier to install thanks to new wireless docking connections and a bezel-less design, resulting in a cabinet depth half as deep as before.3 With modular technology, The 2021 The Wall can be installed in a variety of positions, including concave, convex, ceiling, hanging, inclined and L-type. In addition, users only need to adjust once per cabinet with Factory Seam Adjustment, eliminating module-by-module adjustment and saving time.
       
      The 2021 model offers its most detailed picture yet with the industry’s first 8K resolution with a 120Hz refresh rate and Simple 8K playback. The Wall can be configured horizontally for up to 16K resolution with a 15,360 x 2,160-pixel arrangement.4 Its massive screen measures in at over 1,000 inches, creating a completely expansive canvas for showcasing content.
       

       
      The Wall comes built with Micro HDR and Micro Motion features, featuring 20-bit processing to deliver a consistent picture quality that is suitable across commercial environments for a smooth viewing experience regardless of location. The screen also includes four picture-by-picture screens (PBP), allowing for four different content sources, all of which can be displayed simultaneously in 4K resolution. The 4-PBP function can be used for business purposes where multi-screens are needed.
       
      All of The Wall’s features are delivered with safety top of mind. TÜV Rheinland awarded its Eye Comfort Certification for minimized blue light emission, while its EMC Class B certification minimizes electromagnetic waves for safe installation in homes.
       
      Samsung’s 2021 The Wall is available in select markets around the globe starting today. For more information, please visit: https://displaysolutions.samsung.com/the-wall.
       
       
      1 Figure is based on internal testing standards against Samsung’s conventional LED Signage.
      2 Compared to 2020 model.
      3 Compared to 2020 model.
      4 For a regular design, 16:9 ratio, 8K resolution (7,680 x 4,320) is supported.
      View the full article
    • By STF News
      Today, protecting the environment and fighting climate change require technology manufacturers to take a more thoughtful approach to innovation.
       
      Samsung Electronics strives to incorporate environmental sustainability into everything it does. The company’s products are thoughtfully designed to minimize their impact on the environment throughout their lifecycle – from the planning and manufacturing stages to their use and recycling.
       
      This includes using power-efficient semiconductor chips, sustainable packaging and energy-saving technology, and offering consumers the ability to upcycle packaging and old devices. Through tangible solutions like these, the company is empowering consumers to take part in an important mission: conserving resources and reducing their environmental footprint.
       
      These efforts are reflected in the company’s TV lineup, including its 75-inch Neo QLED TV (QN90A). Check out the infographic below to examine how Samsung took a ‘full circle’ approach to sustainability with one of its latest displays.
       

      View the full article
    • By Alex
      How do you get HBO Go on Samsung Tizen Smart TVs? HBO Go is supported on most Samsung Tizen Smart TVs.
      To find out if HBO GO is available on your Samsung TV, go to Samsung TV: Compatible Devices with HBO GO and look for your Samsung TV model.
      If HBO GO is not available on your Samsung TV, you can use a streaming player (such as Roku or Apple TV), a game console, or stream HBO GO to your TV using Chromecast. 
      Go to Smart Hub and search for HBO Go
       
×
×
  • Create New...