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- Adjust "r.ReadBuffer.MinSize" to a more reasonable default and add "r.ReadBuffer.AlignSize" to so that new buffers are rounded to a reasonable size

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- This fixes massive memory bloat with a Niagara system spawning 10k particles, as each frame we add more particles we were allocating a new buffer.  In the end I saw 94 buffers allocated of varying sizes, the rough memory savings here (at least from a stat POV) is ~70mb.

#rb none
#jira UE-77393
[FYI] shaun.kime, simon.tovey

#ROBOMERGE-OWNER: ben.marsh
#ROBOMERGE-AUTHOR: stu.mckenna
#ROBOMERGE-SOURCE: CL 7644180 via CL 7644917 via CL 7644938
#ROBOMERGE-BOT: BUILD (Main -> Dev-Build) (v388-7785529)

[CL 7788540 by stu mckenna in Dev-Build branch]
This commit is contained in:
stu mckenna
2019-08-06 10:21:49 -04:00
parent fdff23494f
commit 08e6f7c05b
1 changed files with 15 additions and 4 deletions
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19
Engine/Source/Runtime/RenderCore/Private/DynamicBufferAllocator.cpp
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@@ -15,11 +15,20 @@ FAutoConsoleVariableRef CVarMaxReadBufferRenderingBytesAllocatedPerFrame(
GMaxReadBufferRenderingBytesAllocatedPerFrame,
TEXT("The maximum number of transient rendering read buffer bytes to allocate before we start panic logging who is doing the allocations"));
int32 GMinReadBufferRenderingBufferSize = 8 * 1024;
// The allocator works by looking for the first free buffer that contains the required number of elements. There is currently no trim so buffers stay in memory.
// To avoid increasing allocation sizes over multiple frames causing severe memory bloat (i.e. 100 elements, 1001 elements) we first align the required
// number of elements to GMinReadBufferRenderingBufferSize, we then take the max(aligned num, GMinReadBufferRenderingBufferSize)
int32 GMinReadBufferRenderingBufferSize = 256 * 1024;
FAutoConsoleVariableRef CVarMinReadBufferSize(
TEXT("r.ReadBuffer.MinSize"),
GMinReadBufferRenderingBufferSize,
TEXT("The minimum size (in instances) to allocate in blocks for rendering read buffers."));
TEXT("The minimum size (in instances) to allocate in blocks for rendering read buffers. i.e. 256*1024 = 1mb for a float buffer"));
int32 GAlignReadBufferRenderingBufferSize = 64 * 1024;
FAutoConsoleVariableRef CVarAlignReadBufferSize(
TEXT("r.ReadBuffer.AlignSize"),
GAlignReadBufferRenderingBufferSize,
TEXT("The alignment size (in instances) to allocate in blocks for rendering read buffers. i.e. 64*1024 = 256k for a float buffer"));
struct FDynamicReadBufferPool
{
@@ -117,7 +126,8 @@ FGlobalDynamicReadBuffer::FAllocation FGlobalDynamicReadBuffer::AllocateFloat(ui
// Create a new vertex buffer if needed.
if (Buffer == NULL)
{
uint32 NewBufferSize = FMath::Max(Num, (uint32)GMinReadBufferRenderingBufferSize);
const uint32 AlignedNum = FMath::DivideAndRoundUp(Num, (uint32)GAlignReadBufferRenderingBufferSize) * GAlignReadBufferRenderingBufferSize;
const uint32 NewBufferSize = FMath::Max(AlignedNum, (uint32)GMinReadBufferRenderingBufferSize);
Buffer = new FDynamicAllocReadBuffer();
FloatBufferPool->Buffers.Add(Buffer);
Buffer->Initialize(sizeof(float), NewBufferSize, PF_R32_FLOAT, BUF_Dynamic);
@@ -172,7 +182,8 @@ FGlobalDynamicReadBuffer::FAllocation FGlobalDynamicReadBuffer::AllocateInt32(ui
// Create a new vertex buffer if needed.
if (Buffer == NULL)
{
uint32 NewBufferSize = FMath::Max(Num, (uint32)GMinReadBufferRenderingBufferSize);
const uint32 AlignedNum = FMath::DivideAndRoundUp(Num, (uint32)GAlignReadBufferRenderingBufferSize) * GAlignReadBufferRenderingBufferSize;
const uint32 NewBufferSize = FMath::Max(AlignedNum, (uint32)GMinReadBufferRenderingBufferSize);
Buffer = new FDynamicAllocReadBuffer();
Int32BufferPool->Buffers.Add(Buffer);
Buffer->Initialize(sizeof(int32), NewBufferSize, PF_R32_SINT, BUF_Dynamic);