forked from suyu/suyu
58b0ae84b5
This reworks how host<->device synchronization works on the Vulkan backend. Instead of "protecting" resources with a fence and signalling these as free when the fence is known to be signalled by the host GPU, use timeline semaphores. Vulkan timeline semaphores allow use to work on a subset of D3D12 fences. As far as we are concerned, timeline semaphores are a value set by the host or the device that can be waited by either of them. Taking advantange of this, we can have a monolithically increasing atomic value for each submission to the graphics queue. Instead of protecting resources with a fence, we simply store the current logical tick (the atomic value stored in CPU memory). When we want to know if a resource is free, it can be compared to the current GPU tick. This greatly simplifies resource management code and the free status of resources should have less false negatives. To workaround bugs in validation layers, when these are attached there's a thread waiting for timeline semaphores.
63 lines
2 KiB
C++
63 lines
2 KiB
C++
// Copyright 2020 yuzu Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <optional>
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#include "video_core/renderer_vulkan/vk_master_semaphore.h"
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#include "video_core/renderer_vulkan/vk_resource_pool.h"
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namespace Vulkan {
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ResourcePool::ResourcePool(MasterSemaphore& master_semaphore_, size_t grow_step_)
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: master_semaphore{master_semaphore_}, grow_step{grow_step_} {}
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ResourcePool::~ResourcePool() = default;
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size_t ResourcePool::CommitResource() {
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// Refresh semaphore to query updated results
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master_semaphore.Refresh();
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const auto search = [this](size_t begin, size_t end) -> std::optional<size_t> {
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for (size_t iterator = begin; iterator < end; ++iterator) {
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if (master_semaphore.IsFree(ticks[iterator])) {
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ticks[iterator] = master_semaphore.CurrentTick();
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return iterator;
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}
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}
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return {};
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};
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// Try to find a free resource from the hinted position to the end.
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auto found = search(free_iterator, ticks.size());
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if (!found) {
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// Search from beginning to the hinted position.
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found = search(0, free_iterator);
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if (!found) {
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// Both searches failed, the pool is full; handle it.
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const size_t free_resource = ManageOverflow();
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ticks[free_resource] = master_semaphore.CurrentTick();
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found = free_resource;
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}
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}
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// Free iterator is hinted to the resource after the one that's been commited.
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free_iterator = (*found + 1) % ticks.size();
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return *found;
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}
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size_t ResourcePool::ManageOverflow() {
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const size_t old_capacity = ticks.size();
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Grow();
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// The last entry is guaranted to be free, since it's the first element of the freshly
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// allocated resources.
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return old_capacity;
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}
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void ResourcePool::Grow() {
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const size_t old_capacity = ticks.size();
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ticks.resize(old_capacity + grow_step);
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Allocate(old_capacity, old_capacity + grow_step);
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}
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} // namespace Vulkan
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