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Monolith render-thread diff: dev vs p15 (FCL MC 1.21.5 vanilla, H2, cpuhunt)

The fixed function-level baseline for the monolith CPU cuts (SCOREBOARD.md has the fps reference). Every cut starts from a symbolized profile of the p15 side and ends with a before/after of the same function.

Sources:

  • Profiles: simpleperf cpu-clock --trace-offcpu --call-graph fp -f 4000 --duration 6, taken after the measurement windows of an H2 run (FCL pinned to cpu2-6).
  • dev: 08124c99 in runs/safter/dev-Direct{Vulkan,GLES}-r1.
  • p15: p15t = HEAD 3def5cb2 (p15s 0b96a3ef plus the Magma blit view cache) in runs/pt/t-Direct{Vulkan,GLES}-r1.
  • Scope and units: render thread only (the GL thread, which in monolith also applies), off-CPU samples dropped, in ms/frame. Frames are the run's measured fps × 6 s; profiling overhead inflates both sides alike.
  • Reducer: layerdiff.py in the scratchpad.

Attribution: each sample goes to its innermost libMobileGL function, then to one layer.

  • The leaf DSO decides first: driver (Adreno), libc+TLS (libc, libc++, __emutls_get_address, TLS init), or kernel.
  • Otherwise the function's namespace decides:
    • client frontend: MG_Impl, MG_State;
    • pipe record: MG_Pipe validate, tracker and emitters, plus the record channel;
    • applier: MG_Record sinks and record emitters, plus MG_Pipe applier state;
    • backend: MG_Backend.
  • Samples with no libMobileGL frame are app-side (JIT/JVM).

Caveat on function rows: some functions were renamed between dev and p15, so a "+" row and a "-" row can be the same work. Read such pairs together:

  • Espryt FlushPendingRangesNow -> FlushPendingRangesFrom (0.105 -> 0.116);
  • BackendVertexArrayObject::SyncToBackend -> SyncToBackendFromApplier (0.062 -> 0.058);
  • BackendFramebufferObject::SyncToBackend -> SyncToBackendByHandle;
  • Magma SetupDraw -> SetupWireDraw.

Where the excess lives (summary)

layer Magma diff Espryt diff what it is
pipe record +0.36 +0.35 MGPipeValidateForVerb (0.34 inclusive on Magma). Its pieces: framebuffer-state build 0.06, vertex-buffer emit 0.04, global constants 0.03, slot lookups (FindByLifetimeId + Acquire) 0.05, residual CopyField 0.02, tracker 0.02
driver +0.23 +0.06 Magma: per-frame fixed Vulkan work (below). Espryt: about even once renames are paired
libc+TLS +0.22 +0.14 __emutls_get_address 0.055-0.075 plus pGLContext TLS init 0.016 (dev: ~0). Magma: libc under the extra command-buffer and pass begins. Espryt: QueryCurrentSurfaceSize
client frontend +0.12 +0.17 Spread thin. Atomics (__aarch64_ldadd8_*) +0.02, state lookups 0.005 each
backend -0.10 +0.11 Magma's wire backend is cheaper than dev's SetupDraw (no XXH64 vertex-input hash). Espryt pays per-handle registry lookups
JIT/JVM (app) +0.04 +0.08 Not ours; profiling noise between runs

Magma per-frame fixed costs (inclusive ms/frame, dev -> p15):

  • BeginRenderPass 0.045 -> 0.117.
  • EndCommandRecording 0.054 -> 0.113.
  • BeginCommandRecording 0.052 -> 0.089.
  • EndRenderPass 0.023 -> 0.033.
  • Present 0.303 -> 0.352.
  • p15 also has SyncTextureResourceByHandle 0.068, of which UploadPendingWireLevels is 0.038 and FlushPendingCommands 0.025.

Cause: every wire texture upload first submits the frame's recorded work (FlushWirePendingCommandsForTextureUpload) and then uploads in a separate batch. MC updates textures every frame, so the frame pays an extra submit, an extra command-buffer end/begin and a render-pass restart. GpuProgressMarkers::SubmitBracketed is NOT new work: it wraps Present's queue submit, which dev pays inside Present (0.121 vs 0.115).

Espryt-only: QueryCurrentSurfaceSize costs 0.065 ms/frame and dev pays nothing for it. It is two eglQuerySurface calls on every dirty render-state sync (draws 0.048, clears 0.022). It substitutes the surface for a scissor box the app never wrote (and for an empty viewport).

Correction after cut 1 (2026-10-09): what the Magma fixed costs really are

Cut 1 (wire texture uploads stop flushing the frame recording) engaged on device: FlushPendingCommands and SubmitPendingCommandBuffer left the profile, and UploadPendingWireLevels went from 0.038 to 0.016. But Begin/EndCommandRecording and BeginRenderPass did not move. H2 c1: 254.1 -> 249.8 fps, inside the noise.

Their cost is in the driver and scales with what is recorded:

driver call dev p15
vkResetCommandBuffer 0.044 0.077
vkEndCommandBuffer 0.053 0.111
vkCmdBeginRenderPass 0.037 0.105

Host call counts per frame (diagnostic counting builds; FCL vanilla; 600-frame windows):

  • Magma, Vulkan calls: dev 331.6 vs p15 379.
    • The draw-level stream is identical and almost free of repeats: DrawIndexed 86.1, BindVertexBuffers 87.1, BindDescriptorSets 87.1, BindPipeline 15.1, UpdateDescriptorSets 14, dynamic state 2 each.
    • Render passes: 4.1 -> 12.6.
    • Pipeline barriers: 3.4 -> 27.5.
    • CopyBufferToImage: 0.1 -> 2.2.
    • By call site (unwinding counter):
      • Pass begins: 6.5 at draws, 5.2 at clears, 1 at the blit.
      • Pass ends: 5.3 from ResolveWireImageDescriptor (sampling an image written earlier), 4.2 from TransitionWireImage in the in-pass clear, 1.2 from TransitionWireImage in SetupWireDraw, 2 at the blit.
      • Barriers: 11.8 from TransitionWireImage at draw-pass begin, 6.3 at clear-pass begin, 5.6 from ResolveWireImageDescriptor, 2 at the blit, 1 at present.
    • Cause: each new wire draw pass runs TransitionWireImage(GENERAL -> GENERAL) per attachment. That ends the open pass and records a full ALL_COMMANDS memory barrier whether or not a hazard exists.
  • Espryt, host GLES calls: dev 850.7 (479 repeat their previous arguments) vs p15 835.6 (446).
    • p15 does not issue more GLES calls than dev.
    • In both, most of the repeats are glVertexAttribPointer 302 + glVertexAttribIPointer 75: the same layout re-pointed at a new VBO on every draw.

Levers beyond the local cuts (evaluated 2026-10-09)

Estimates are ms/frame of FCL GL-thread CPU. "Measured" rows come from H2 A/Bs (SCOREBOARD).

lever result status
Pipe batch (FB memo, handle hints, buffer reuse, gate cache, Magma hash TLS) measured: Magma -0.06, Espryt -0.03 landed 485dff14, c85c9439
ThinLTO + -O3 + ICF/gc (gradle default ON) measured: Magma -0.16 (2.52 -> 2.36), Espryt -0.09 190580f2 (coordinator pushes)
Magma rename spares 4 -> 12 + fence-poll quiet window profile ceiling ~0.05-0.06 (Create 0.031, Destroy 0.014, vkGetFenceStatus 0.020) a0015bad; m2ab A/B
API 29 separate artifact (native ELF TLS) estimate 0.08-0.1 (emutls 0.054 + pGLContext TLS init 0.024 on Magma) wip/api29-switch, A/B open
AutoFDO/PGO estimate 0.1-0.25 with the user
Emulated-TLS work below 29 (mirror, owner-thread path, dual lib) estimate 0.024-0.08 dropped by the user
App-side JIT delta +0.065 vs dev (0.708 -> 0.773 app-only), cause unknown needs a GL entry-count A/B
shared_ptr refcount avoidance in bind paths 0.005-0.01 not started
Espryt VertexAttribPointer split <=0.04 parked

Cuts, biggest first

Revised order:

  1. 1b (Magma): explicit external subpass dependencies on the wire draw passes. Barrier only images last written by transfer or storage, once and coalesced before the pass. Estimate: passes 12.6 -> ~5, barriers 27 -> ~5, and the driver's command-buffer and pass-begin cost with them.
  2. Cut 1 stays local (no measurable gain).

Order from 2026-10-09:

  1. 1c deferred clears (PARITY-AUDIT M1).
  2. The remaining Magma barriers.
  3. The pipe-record pieces.
  4. The TLS hoist.

Measured and parked: Espryt glVertexAttribPointer -> glBindVertexBuffer + glVertexAttribFormat.

  • Ceiling: SyncToBackendFromApplier costs 0.060 ms/frame inclusive, driver calls included (0.015 self). Source: the c4 p15w Espryt profile, cpuhunt.
  • The repeats are MC's per-draw re-point: the same layout with a new buffer at offset 0, about 4 attributes per buffer. The split would turn 1 glBindBuffer + ~4 pointer calls into 1 glBindVertexBuffer.
  • Expected saving: ~0.02-0.04 ms/frame. That is below H2 resolution (1.2-2.9% spread).
  • Cost: a second VAO shadow (format + binding). ES glVertexAttribPointer and glVertexAttribDivisor silently rebind attribute -> binding, so the change is correctness-sensitive.

The original list follows.

Estimates are ms/frame on the H2 render thread. Each cut gets a before/after profile of its function and an H2 A/B.

  1. Magma: record wire texture uploads into the frame's command buffer instead of flush + separate batch. Estimate 0.10-0.15. It removes the extra submit, the command-buffer end/begin and the pass restart. Correctness-sensitive: draw / TexSubImage / draw ordering, and staging lifetime per frame. Red-once with the existing between-draws upload scenarios, plus syncval.
  2. Shared: the pipe-record layer, about 0.35 on both backends. Parts:
    • (a) framebuffer-state build per verb: memo on the framebuffer's version;
    • (b) slot lookups by lifetime id;
    • (c) residual CopyField on monolith, where fillOwed is always true;
    • (d) vertex-buffer and global-constant emit. Each part is 0.02-0.06. Profile-driven, one at a time.
  3. Shared: TLS. __emutls_get_address plus TLS init is ~0.07-0.09. The structural fix is native TLS (minSdk, the user's call). The in-code mitigation is to read pGLContext / gPipeInputs once per verb and pass the pointer down.
  4. Espryt: memoize the surface size per draw surface, invalidated at swap and make-current. Estimate 0.06.
  5. Magma: the clear path (glClear 0.285 vs dev ~0.13): first re-profile after cut 1, since much of it is the command-buffer and pass begins cut 1 removes.

Magma (DirectVulkan): +0.88 ms/frame on the render thread (schedstat: 2.84 vs 2.00)

layer dev p15 diff
client frontend 0.257 0.376 +0.119
pipe record 0.000 0.363 +0.363
applier 0.000 0.026 +0.026
backend 0.516 0.416 -0.100
driver 0.394 0.622 +0.228
libc+TLS 0.213 0.430 +0.218
kernel (from MobileGL) 0.112 0.115 +0.003
mgl other 0.066 0.049 -0.017
JIT/JVM (app) 0.659 0.697 +0.038
kernel (app) 0.049 0.047 -0.001
total 2.265 3.142 +0.877

Top 15 p15 excess rows:

layer function (attributed) dev p15 diff
libc+TLS __emutls_get_address 0.000 0.075 +0.075
driver VkRenderPassManager::BeginRenderPass 0.029 0.081 +0.052
driver FrameContext::EndCommandRecording 0.045 0.090 +0.045
kernel (from MobileGL) GpuProgressMarkers::SubmitBracketed 0.000 0.045 +0.045
driver VulkanRenderer::SetupWireDraw 0.000 0.040 +0.040
pipe record MG_Pipe::MGPipeValidateForVerb 0.000 0.035 +0.035
backend VulkanRenderer::SetupWireDraw 0.000 0.034 +0.034
driver VulkanRenderer::DrawElements 0.101 0.129 +0.028
pipe record MG_Pipe::MGPipeSlotAllocator::FindByLifetimeId 0.000 0.026 +0.026
driver GpuProgressMarkers::SubmitBracketed 0.000 0.024 +0.024
driver UniformManager::ResolveWireImageDescriptor 0.000 0.023 +0.023
pipe record MG_Pipe::MGPipeTracker::Update 0.000 0.022 +0.022
libc+TLS VkRenderPassManager::BeginRenderPass 0.010 0.032 +0.022
libc+TLS FrameContext::BeginCommandRecording 0.018 0.039 +0.021

Per layer (top 6 each):

layer function (attributed) dev p15 diff
client frontend __aarch64_ldadd8_acq_rel 0.013 0.023 +0.010
client frontend MG_State::GLState::FramebufferAttachmentObject::IsEmpty 0.000 0.008 +0.007
client frontend MG_State::GLState::BufferState::GetBindingSlot 0.000 0.006 +0.006
client frontend __aarch64_ldadd8_relax 0.004 0.010 +0.006
client frontend MG_State::GLState::ShareGroupState::GetBufferObject 0.000 0.005 +0.005
client frontend MG_State::GLState::FramebufferObject::CheckCompleteness 0.000 0.004 +0.004
pipe record MG_Pipe::MGPipeValidateForVerb 0.000 0.035 +0.035
pipe record MG_Pipe::MGPipeSlotAllocator::FindByLifetimeId 0.000 0.026 +0.026
pipe record MG_Pipe::MGPipeTracker::Update 0.000 0.022 +0.022
pipe record MG_Pipe::MGPipeFillAccess::CopyField 0.000 0.021 +0.021
pipe record MG_Pipe::MGPipeVertexInputEmitter::EmitVertexBuffers 0.000 0.018 +0.018
pipe record MG_Pipe::MGPipeProgramEmitter::EmitGlobalConstants 0.000 0.011 +0.011
applier MG_Record::RecordVerbSink::OnDrawVbo 0.000 0.005 +0.005
applier MG_Record::{anon}::EmitDrawRecord 0.000 0.004 +0.004
applier MG_Record::{anon}::EmitClear 0.000 0.003 +0.003
applier MG_Record::{anon}::EmitIndexedDraw 0.000 0.003 +0.003
applier MG_Record::{anon}::EmitDrawElements 0.000 0.003 +0.003
applier MG_Pipe::MGPipeApplierState::DrawFramebuffer 0.000 0.003 +0.003
backend VulkanRenderer::SetupWireDraw 0.000 0.034 +0.034
backend VulkanRenderer::GetOrCreatePipelineWithInput 0.000 0.021 +0.021
backend UniformManager::PrepareWireTextureResources 0.000 0.018 +0.018
backend _t const&, std::__ndk1::tuple<unsigned long const&>, std::__ndk1::tuple<> > 0.000 0.016 +0.016
backend UniformManager::ResolveWireImageDescriptor 0.000 0.014 +0.014
backend VkTextureManager::ResolveWireTextureStorage 0.000 0.012 +0.012
driver VkRenderPassManager::BeginRenderPass 0.029 0.081 +0.052
driver FrameContext::EndCommandRecording 0.045 0.090 +0.045
driver VulkanRenderer::SetupWireDraw 0.000 0.040 +0.040
driver VulkanRenderer::DrawElements 0.101 0.129 +0.028
driver GpuProgressMarkers::SubmitBracketed 0.000 0.024 +0.024
driver UniformManager::ResolveWireImageDescriptor 0.000 0.023 +0.023
libc+TLS __emutls_get_address 0.000 0.075 +0.075
libc+TLS VkRenderPassManager::BeginRenderPass 0.010 0.032 +0.022
libc+TLS FrameContext::BeginCommandRecording 0.018 0.039 +0.021
libc+TLS thread-local initialization routine for MG_State::pGLContext 0.000 0.017 +0.017
libc+TLS EndActiveRenderPassOn 0.000 0.014 +0.014
libc+TLS FrameContext::EndCommandRecording 0.009 0.023 +0.014

Espryt (DirectGLES): +0.93 ms/frame on the render thread (schedstat: 3.13 vs 2.34)

layer dev p15 diff
client frontend 0.238 0.404 +0.166
pipe record 0.000 0.349 +0.349
applier 0.000 0.041 +0.041
backend 0.245 0.356 +0.111
driver 0.800 0.861 +0.062
libc+TLS 0.209 0.350 +0.141
kernel (from MobileGL) 0.209 0.221 +0.011
mgl other 0.134 0.113 -0.021
JIT/JVM (app) 0.693 0.774 +0.081
kernel (app) 0.055 0.050 -0.005
total 2.584 3.518 +0.935

Top 15 p15 excess rows:

layer function (attributed) dev p15 diff
driver BufferImpl::{anon}::FlushPendingRangesFrom 0.000 0.091 +0.091
libc+TLS __emutls_get_address 0.000 0.055 +0.055
driver VertexArrayImpl::BackendVertexArrayObject::SyncToBackendFromApplier 0.000 0.040 +0.040
pipe record MG_Pipe::MGPipeValidateForVerb 0.000 0.040 +0.040
driver DrawElements 0.276 0.312 +0.036
pipe record MG_Pipe::MGPipeTracker::Update 0.000 0.029 +0.029
libc+TLS QueryCurrentSurfaceSize 0.000 0.026 +0.026
libc+TLS BufferImpl::{anon}::FlushPendingRangesFrom 0.000 0.025 +0.025
driver FramebufferImpl::BackendFramebufferObject::SyncToBackendByHandle 0.000 0.025 +0.025
mgl other QueryCurrentSurfaceSize 0.000 0.023 +0.023
pipe record MG_Pipe::MGPipeSlotAllocator::FindByLifetimeId 0.000 0.022 +0.022
pipe record MG_Pipe::MGPipeVertexInputEmitter::EmitVertexBuffers 0.000 0.021 +0.021
pipe record MG_Pipe::MGPipeFillAccess::CopyField 0.000 0.018 +0.018
backend VertexArrayImpl::BackendVertexArrayObject::SyncToBackendFromApplier 0.000 0.018 +0.018

Per layer (top 6 each):

layer function (attributed) dev p15 diff
client frontend __aarch64_ldadd8_acq_rel 0.012 0.026 +0.014
client frontend __aarch64_ldadd8_relax 0.003 0.013 +0.011
client frontend MG_State::GLState::FramebufferAttachmentObject::IsEmpty 0.000 0.006 +0.006
client frontend MG_State::GLState::ShareGroupState::ValidateBufferObject 0.000 0.006 +0.006
client frontend MG_State::GLState::BufferState::GetBindingSlot 0.001 0.006 +0.005
client frontend MG_State::GLState::GLContext::GetProgramForDraw 0.002 0.007 +0.005
pipe record MG_Pipe::MGPipeValidateForVerb 0.000 0.040 +0.040
pipe record MG_Pipe::MGPipeTracker::Update 0.000 0.029 +0.029
pipe record MG_Pipe::MGPipeSlotAllocator::FindByLifetimeId 0.000 0.022 +0.022
pipe record MG_Pipe::MGPipeVertexInputEmitter::EmitVertexBuffers 0.000 0.021 +0.021
pipe record MG_Pipe::MGPipeFillAccess::CopyField 0.000 0.018 +0.018
pipe record MG_Pipe::MGPipeProgramEmitter::EmitGlobalConstants 0.000 0.009 +0.009
applier MG_Record::RecordVerbSink::OnDrawVbo 0.000 0.009 +0.009
applier MG_Record::{anon}::EmitDrawRecord 0.000 0.009 +0.009
applier MG_Pipe::MGPipeApplierState::DrawFramebuffer 0.000 0.005 +0.005
applier MG_Record::{anon}::EmitIndexedDraw 0.000 0.004 +0.004
applier MG_Record::{anon}::EmitDrawElements 0.000 0.002 +0.002
applier MG_Pipe::MGPipeApplierState::ReadFramebuffer 0.000 0.002 +0.002
backend VertexArrayImpl::BackendVertexArrayObject::SyncToBackendFromApplier 0.000 0.018 +0.018
backend TextureImpl::BackendTextureObject::IsDrawSyncCleanByRecord 0.000 0.013 +0.013
backend BufferImpl::EnsureBufferResourceForHandle 0.000 0.012 +0.012
backend eRegistry<MG_State::GLState::BufferObject, BufferImpl::GLESBufferResource, 0.000 0.011 +0.011
backend stry<MG_State::GLState::ITextureObject, TextureImpl::BackendTextureObject, 0.000 0.010 +0.010
backend ry<MG_State::GLState::ProgramObject, PrgramImpl::BackendProgramObjectImpl, 0.000 0.009 +0.009
driver BufferImpl::{anon}::FlushPendingRangesFrom 0.000 0.091 +0.091
driver VertexArrayImpl::BackendVertexArrayObject::SyncToBackendFromApplier 0.000 0.040 +0.040
driver DrawElements 0.276 0.312 +0.036
driver FramebufferImpl::BackendFramebufferObject::SyncToBackendByHandle 0.000 0.025 +0.025
driver QueryCurrentSurfaceSize 0.000 0.016 +0.016
driver PrepareForDraw 0.005 0.010 +0.005
libc+TLS __emutls_get_address 0.000 0.055 +0.055
libc+TLS QueryCurrentSurfaceSize 0.000 0.026 +0.026
libc+TLS BufferImpl::{anon}::FlushPendingRangesFrom 0.000 0.025 +0.025
libc+TLS thread-local initialization routine for MG_State::pGLContext 0.000 0.016 +0.016
libc+TLS TextureImpl::SyncTextureToBackendByHandle 0.000 0.013 +0.013
libc+TLS FramebufferImpl::BackendFramebufferObject::SyncToBackendByHandle 0.000 0.007 +0.007
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