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VMM  ·  Vulkan Memory Manager

Persistent · transient · frame-buffered — three lifetimes, one staging ring

Three-layer GPU resource lifecycle. Optional — the core works fine with raw VulkanBuffer / VulkanImage. Use VMM when you want batched staging uploads, a zero-cost per-frame transient pool, or lifetime-tagged persistent allocations.

Layers

Layer 1  VmmRawAlloc          thin typed VMA wrappers
Layer 2  VmmRegistry          every allocation tagged with a Lifetime
Layer 3  VulkanMemoryManager  pools and strategies

Lifetimes

Lifetime Behaviour
Persistent Freed at Shutdown or explicit FreeBuffer / FreeImage.
TransientFrame Auto-freed when the frame slot it was allocated in comes around again.
FrameBuffered One instance per frame slot.
Manual Registry tracks it for stats only; caller frees it.

Strategies

  • StagingRing — single CPU-visible ring for batched uploads. StageToBuffer / StageToImage queue copies; EndFrame / FlushStaging submit the batch.
  • TransientPool — one CPU→GPU block per frame slot, persistently mapped. Zero-cost pointer bumps; reset on BeginFrame.
  • Persistent allocations — textures, static meshes, anything that outlives a frame.

Typical frame (outside FrameScheduler)

vkWaitForFences(..., sync.GetInFlightFence(slot), ...);   // MUST come first
vmm.BeginFrame(slot, absoluteFrame);

VCK::VmmBuffer dyn = vmm.AllocTransient(slot, "ui_verts",
                                        size, VK_BUFFER_USAGE_VERTEX_BUFFER_BIT);
dyn.Upload(data, size);

// ... record draws ...

vmm.EndFrame(slot);   // submits staging batch, resets ring

Persistent + staged upload

VCK::VmmBuffer vb = vmm.AllocPersistent("static-verts", size,
                                        VK_BUFFER_USAGE_VERTEX_BUFFER_BIT |
                                        VK_BUFFER_USAGE_TRANSFER_DST_BIT);
vmm.StageToBuffer(vb, src, size);
vmm.FlushStaging();     // one-shot submit + wait + ring reset

Persistent image + staged upload

VCK::VmmImage img = vmm.AllocPersistentImage(
    "texture", width, height, VK_FORMAT_R8G8B8A8_SRGB,
    VK_IMAGE_USAGE_SAMPLED_BIT | VK_IMAGE_USAGE_TRANSFER_DST_BIT);
vmm.StageToImage(img, pixels, pixelsBytes);
vmm.FlushStaging();

Stats

vmm.LogStats();    // registry + staging ring + transient pool snapshot

Use it as a sanity check: it prints per-lifetime counts, total bytes, and the staging ring's current high-water mark.

Current caveats

  • v0.3: VulkanMemoryManager::SubmitStagingCmd now uses a per-submit VkFence (no vkQueueWaitIdle). When the transfer queue is dedicated, staging submits to the transfer family and records a release/acquire ownership-barrier pair so the graphics queue sees the expected image layout (Vulkan §7.7.4). The acquire is CPU-serialised today — a semaphore-driven async acquire is on the v0.4 roadmap.
  • v0.3: The staging ring still resets at the end of each EndFrame / FlushStaging; per-frame staging is still the recommended pattern for pipelined uploads.
  • VulkanOneTimeCommand::End uses a short-circuiting vkWaitForFences so a failed submit no longer hangs the caller (v0.3 fix).