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Improved documentation - added "Custom memory pools" > "Choosing memory type index"

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Adam Sawicki 2018-02-19 17:28:35 +01:00
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docs/html/custom_memory_pools.html
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@ -80,7 +80,11 @@ $(function() {
</ol>
<p>Example:</p>
<div class="fragment"><div class="line"><span class="comment">// Create a pool that could have at most 2 blocks, 128 MiB each.</span></div><div class="line"><a class="code" href="struct_vma_pool_create_info.html">VmaPoolCreateInfo</a> poolCreateInfo = {};</div><div class="line">poolCreateInfo.<a class="code" href="struct_vma_pool_create_info.html#a596fa76b685d3f1f688f84a709a5b319">memoryTypeIndex</a> = ...</div><div class="line">poolCreateInfo.blockSize = 128ull * 1024 * 1024;</div><div class="line">poolCreateInfo.<a class="code" href="struct_vma_pool_create_info.html#ae41142f2834fcdc82baa4883c187b75c">maxBlockCount</a> = 2;</div><div class="line"></div><div class="line">VmaPool pool;</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#a5c8770ded7c59c8caac6de0c2cb00b50">vmaCreatePool</a>(allocator, &amp;poolCreateInfo, &amp;pool);</div><div class="line"></div><div class="line"><span class="comment">// Allocate a buffer out of it.</span></div><div class="line">VkBufferCreateInfo bufCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };</div><div class="line">bufCreateInfo.size = 1024;</div><div class="line">bufCreateInfo.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT;</div><div class="line"></div><div class="line"><a class="code" href="struct_vma_allocation_create_info.html">VmaAllocationCreateInfo</a> allocCreateInfo = {};</div><div class="line">allocCreateInfo.<a class="code" href="struct_vma_allocation_create_info.html#a6272c0555cfd1fe28bff1afeb6190150">pool</a> = pool;</div><div class="line"></div><div class="line">VkBuffer buf;</div><div class="line">VmaAllocation alloc;</div><div class="line"><a class="code" href="struct_vma_allocation_info.html">VmaAllocationInfo</a> allocInfo;</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#ac72ee55598617e8eecca384e746bab51">vmaCreateBuffer</a>(allocator, &amp;bufCreateInfo, &amp;allocCreateInfo, &amp;buf, &amp;alloc, &amp;allocInfo);</div></div><!-- fragment --><p>You have to free all allocations made from this pool before destroying it.</p>
<div class="fragment"><div class="line"><a class="code" href="vk__mem__alloc_8h.html#a0d9f4e4ba5bf9aab1f1c746387753d77">vmaDestroyBuffer</a>(allocator, buf, alloc);</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#a5485779c8f1948238fc4e92232fa65e1">vmaDestroyPool</a>(allocator, pool);</div></div><!-- fragment --> </div></div><!-- contents -->
<div class="fragment"><div class="line"><a class="code" href="vk__mem__alloc_8h.html#a0d9f4e4ba5bf9aab1f1c746387753d77">vmaDestroyBuffer</a>(allocator, buf, alloc);</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#a5485779c8f1948238fc4e92232fa65e1">vmaDestroyPool</a>(allocator, pool);</div></div><!-- fragment --><h1><a class="anchor" id="custom_memory_pools_MemTypeIndex"></a>
Choosing memory type index</h1>
<p>When creating a pool, you must explicitly specify memory type index. To find the one suitable for your buffers or images, you can use code similar to the following:</p>
<div class="fragment"><div class="line">VkBufferCreateInfo dummyBufCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };</div><div class="line">dummyBufCreateInfo.size = 1024; <span class="comment">// Whatever.</span></div><div class="line">dummyBufCreateInfo.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT; <span class="comment">// Change if needed.</span></div><div class="line"></div><div class="line">VkBuffer dummyBuf;</div><div class="line">vkCreateBuffer(device, &amp;dummyBufCreateInfo, <span class="keyword">nullptr</span>, &amp;dummyBuf);</div><div class="line"></div><div class="line">VkMemoryRequirements memReq;</div><div class="line">vkGetBufferMemoryRequirements(device, dummyBuf, &amp;memReq);</div><div class="line"></div><div class="line"><a class="code" href="struct_vma_allocation_create_info.html">VmaAllocationCreateInfo</a> allocCreateInfo = {};</div><div class="line">allocCreateInfo.<a class="code" href="struct_vma_allocation_create_info.html#accb8b06b1f677d858cb9af20705fa910">usage</a> = <a class="code" href="vk__mem__alloc_8h.html#aa5846affa1e9da3800e3e78fae2305ccac6b5dc1432d88647aa4cd456246eadf7">VMA_MEMORY_USAGE_GPU_ONLY</a>; <span class="comment">// Change if needed.</span></div><div class="line"></div><div class="line">uint32_t memTypeIndex;</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#aef15a94b58fbcb0fe706d5720e84a74a">vmaFindMemoryTypeIndex</a>(allocator, memReq.memoryTypeBits, &amp;allocCreateInfo, &amp;memTypeIndex);</div><div class="line"></div><div class="line">vkDestroyBuffer(device, dummyBuf, <span class="keyword">nullptr</span>);</div><div class="line"></div><div class="line"><a class="code" href="struct_vma_pool_create_info.html">VmaPoolCreateInfo</a> poolCreateInfo = {};</div><div class="line">poolCreateInfo.<a class="code" href="struct_vma_pool_create_info.html#a596fa76b685d3f1f688f84a709a5b319">memoryTypeIndex</a> = memTypeIndex;</div><div class="line"><span class="comment">// ...</span></div></div><!-- fragment --><p>Dummy buffer is needed to query driver for <code>memReq.memoryTypeBits</code>. Memory is never allocated for this buffer. You should fill structures <code>dummyBufCreateInfo</code> and <code>allocCreateInfo</code> with the same parameters as you are going to use for buffers created in your pool. </p>
</div></div><!-- contents -->
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@ -711,7 +711,7 @@ Functions</h2></td></tr>
<table class="fieldtable">
<tr><th colspan="2">Enumerator</th></tr><tr><td class="fieldname"><a id="aa5846affa1e9da3800e3e78fae2305ccaf50d27e34e0925cf3a63db8c839121dd"></a>VMA_MEMORY_USAGE_UNKNOWN&#160;</td><td class="fielddoc"><p>No intended memory usage specified. Use other members of <a class="el" href="struct_vma_allocation_create_info.html">VmaAllocationCreateInfo</a> to specify your requirements. </p>
</td></tr>
<tr><td class="fieldname"><a id="aa5846affa1e9da3800e3e78fae2305ccac6b5dc1432d88647aa4cd456246eadf7"></a>VMA_MEMORY_USAGE_GPU_ONLY&#160;</td><td class="fielddoc"><p>Memory will be used on device only, so fast access from the device is preferred. It usually means device-local GPU (video) memory. No need to be mappable on host.</p>
<tr><td class="fieldname"><a id="aa5846affa1e9da3800e3e78fae2305ccac6b5dc1432d88647aa4cd456246eadf7"></a>VMA_MEMORY_USAGE_GPU_ONLY&#160;</td><td class="fielddoc"><p>Memory will be used on device only, so fast access from the device is preferred. It usually means device-local GPU (video) memory. No need to be mappable on host. It is roughly equivalent of D3D12_HEAP_TYPE_DEFAULT.</p>
<p>Usage:</p>
<ul>
<li>Resources written and read by device, e.g. images used as attachments.</li>
@ -719,13 +719,13 @@ Functions</h2></td></tr>
</ul>
<p>Allocation may still end up in <code>HOST_VISIBLE</code> memory on some implementations. In such case, you are free to map it. You can use <code>VMA_ALLOCATION_CREATE_MAPPED_BIT</code> with this usage type. </p>
</td></tr>
<tr><td class="fieldname"><a id="aa5846affa1e9da3800e3e78fae2305cca40bdf4cddeffeb12f43d45ca1286e0a5"></a>VMA_MEMORY_USAGE_CPU_ONLY&#160;</td><td class="fielddoc"><p>Memory will be mappable on host. It usually means CPU (system) memory. Resources created in this pool are still accessible to the device, but access to them can be slower. Guarantees to be <code>HOST_VISIBLE</code> and <code>HOST_COHERENT</code>. CPU read may be uncached.</p>
<tr><td class="fieldname"><a id="aa5846affa1e9da3800e3e78fae2305cca40bdf4cddeffeb12f43d45ca1286e0a5"></a>VMA_MEMORY_USAGE_CPU_ONLY&#160;</td><td class="fielddoc"><p>Memory will be mappable on host. It usually means CPU (system) memory. Resources created in this pool are still accessible to the device, but access to them can be slower. Guarantees to be <code>HOST_VISIBLE</code> and <code>HOST_COHERENT</code>. CPU read may be uncached. It is roughly equivalent of D3D12_HEAP_TYPE_UPLOAD.</p>
<p>Usage: Staging copy of resources used as transfer source. </p>
</td></tr>
<tr><td class="fieldname"><a id="aa5846affa1e9da3800e3e78fae2305cca9066b52c5a7079bb74a69aaf8b92ff67"></a>VMA_MEMORY_USAGE_CPU_TO_GPU&#160;</td><td class="fielddoc"><p>Memory that is both mappable on host (guarantees to be <code>HOST_VISIBLE</code>) and preferably fast to access by GPU. CPU reads may be uncached and very slow.</p>
<p>Usage: Resources written frequently by host (dynamic), read by device. E.g. textures, vertex buffers, uniform buffers updated every frame or every draw call. </p>
</td></tr>
<tr><td class="fieldname"><a id="aa5846affa1e9da3800e3e78fae2305cca7b586d2fdaf82a463b58f581ed72be27"></a>VMA_MEMORY_USAGE_GPU_TO_CPU&#160;</td><td class="fielddoc"><p>Memory mappable on host (guarantees to be <code>HOST_VISIBLE</code>) and cached.</p>
<tr><td class="fieldname"><a id="aa5846affa1e9da3800e3e78fae2305cca7b586d2fdaf82a463b58f581ed72be27"></a>VMA_MEMORY_USAGE_GPU_TO_CPU&#160;</td><td class="fielddoc"><p>Memory mappable on host (guarantees to be <code>HOST_VISIBLE</code>) and cached. It is roughly equivalent of D3D12_HEAP_TYPE_READBACK.</p>
<p>Usage:</p>
<ul>
<li>Resources written by device, read by host - results of some computations, e.g. screen capture, average scene luminance for HDR tone mapping.</li>

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@ -363,6 +363,41 @@ vmaDestroyBuffer(allocator, buf, alloc);
vmaDestroyPool(allocator, pool);
\endcode
\section custom_memory_pools_MemTypeIndex Choosing memory type index
When creating a pool, you must explicitly specify memory type index.
To find the one suitable for your buffers or images, you can use code similar to the following:
\code
VkBufferCreateInfo dummyBufCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
dummyBufCreateInfo.size = 1024; // Whatever.
dummyBufCreateInfo.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT; // Change if needed.
VkBuffer dummyBuf;
vkCreateBuffer(device, &dummyBufCreateInfo, nullptr, &dummyBuf);
VkMemoryRequirements memReq;
vkGetBufferMemoryRequirements(device, dummyBuf, &memReq);
VmaAllocationCreateInfo allocCreateInfo = {};
allocCreateInfo.usage = VMA_MEMORY_USAGE_GPU_ONLY; // Change if needed.
uint32_t memTypeIndex;
vmaFindMemoryTypeIndex(allocator, memReq.memoryTypeBits, &allocCreateInfo, &memTypeIndex);
vkDestroyBuffer(device, dummyBuf, nullptr);
VmaPoolCreateInfo poolCreateInfo = {};
poolCreateInfo.memoryTypeIndex = memTypeIndex;
// ...
\endcode
Dummy buffer is needed to query driver for `memReq.memoryTypeBits`.
Memory is never allocated for this buffer.
You should fill structures `dummyBufCreateInfo` and `allocCreateInfo` with the same parameters
as you are going to use for buffers created in your pool.
\page defragmentation Defragmentation
Interleaved allocations and deallocations of many objects of varying size can