MobileGL/docs/Disaggregated/notes/perf-p14/HANDOFF.md

P14 perf pass: handoff (closed 2026-10-07)

The pass is closed at 781a7446, plus this docs commit. Results are in BENCH.md and README.md. The next phase is the per-(VAO, program) draw-packet cache (NEXT-draw-packet-cache.md). Its first item is an off-CPU profile of FCL Magma monolith (README "Headline numbers").

Where things stand (rd12, pinned, FINISH=false, best of 3)

arm	Espryt	Magma	dev Espryt / Magma
monolith	91.1	83.8	115.2 / 87.0
inproc	111.9	110.0
shm	87.8	95.6
tcp	68.7	69.9

FCL MC in world:

• dev: Espryt 228.6, Magma 231.8;
• feat monolith: Espryt 198.3, Magma 171.4;
• feat inproc: Espryt 241.5, Magma 194.8.

All arms are CPU-bound (GPU 19-39 %).

Open items (DEBTS.md has the rows)

1. FCL Magma monolith waits about 3 ms/frame. The trace does not show it. Profile it off-CPU first. Both close-out attempts caught no game frames, because FCL start-up ran past the 60 s warm-up.
2. The draw-packet cache (design sketch). Prototype the client half on Espryt monolith first.
3. The Espryt driver +0.33 ms is a cache-pressure inference. Check it with L1D refills before and after (2).
4. Native TLS, minSdk 29 vs 26, is the user's call: +1.7 % Espryt, noise on Magma.

Harness

Session scratchpad scripts:

• build_trace.sh W:/perf .p14X: trace APK, package top.mobilegl.plugin.p14X.trace.
• sign_install.sh <apk> <name>.
• devjob.sh <log> <cmd>: runs a device job under a mkdir lock. Always use it; two concurrent device jobs contaminate each other, and killing a job leaves its children running.
• incl.py / children.py / lines.py / layers2.py / drvcall.py / offcpu.py: simpleperf analyses. The tail window comes from the render thread's retraceCall samples.
• profile_offcpu.sh: --trace-offcpu variant of profile_p14.sh.
• stat_p14.sh: simpleperf stat counters.
• fcl_offcpu.sh: FCL profile plus restore.

Then:

cd tools/device_bench/disagg
FIXTURES=<main checkout>/tools/trace_replay/fixtures PREP_PKGS=top.mobilegl.plugin.p14X.trace bash matrix_p14.sh prep
ARMS="monolith@p14a monolith@p14b" BACKENDS="DirectGLES DirectVulkan" WLS=rd12 REPS=3 TAG=ab bash matrix_p14.sh run
python p14_report.py ../../../.trace-work/perf-p14/ab
ARMS="monolith@p14X inproc@p14X shm@p14X tcp@p14X" REPS=1 TAG=ssim bash matrix_p14.sh ssim   # SSIM gate
ARM=monolith BACKEND=DirectGLES WL=rd12 TAG=prof PKG_FEAT=... SYMDIR=<unstripped libs> bash profile_p14.sh

The FCL library comes from :app:assemblePluginRelease. Unzip lib/arm64-v8a/libMobileGL.so from app/build/outputs/apk/plugin/release/; the unstripped copy is under intermediates/merged_native_libs/pluginRelease. Run fcl_p14.sh run, then restore (md5-checked).

Gradle's packageTraceRelease sometimes fails on the first try with IncrementalSplitterRunnable; a rerun succeeds.

Host:

• Unit tests: WSL archlinux ~/mgl-perf-bld (clang, split + inproc).
  • ServerSpawnTest, FuzzArm2 and PeerLatchTest fail there with Refuse{BuildFingerprint}; that is environmental.
  • The google-benchmark targets don't build with clang 22; also environmental.
• CI-shaped integration tree: ~/mgl-perf-ci31, configured with CMake 3.31.10 from the ~/mgl-perf-tools venv.
  • The system CMake 4.x joins gtest_discover_tests ENVIRONMENT lists into one variable, and every entry then skips. Use 3.31.10.
  • lavapipe ICD; spawn/tcp lanes are environmental there.
  • To run the syncval gates: scripts/ci/magma_runahead_checks.py validation --build-dir ~/mgl-perf-ci31 --execute, with GIT_DIR=.../.git/modules/MobileGL/worktrees/perf set for the cache script.
• ~/mgl-perf-ci is a CMake 4 tree. Use it only through the scratchpad's runentry.sh, which splits the joined environment.

Device state

• HA27Q3LQ CPU/GPU clocks are still PINNED: the next phase wants them pinned. bash pin_clocks.sh restore undoes it; ask before unpinning.
• FCL is restored: lib md5 matches /data/local/tmp/p14-fcl-orig.so, config.json matches its saved copy, and the debug.mobilegl.* properties are deleted.
• Trace APKs top.mobilegl.plugin.p14*.trace are installed; p14fin is the close-out build.

CI

Dispatched runs (workflow_dispatch, not cancelled by later pushes):

• 86ab2835: Test 37702990844, APK 37702995519.
• 781a7446: Test 37707221661.
• The close-out docs head: see the final report.

Every runs-on in test.yml is GitHub-hosted ubuntu-latest, so long queueing is GitHub capacity / max-parallel, not a runner of ours. PeerLatch.SiteMap (scripts/ci/ph_latch_sites.py) greps ServerLoop.cpp's text: keep its patterns in step when DrainRing's shape changes (it caught the DrainRing(polledHead) signature at a0f4aa83). Locally, filter environmental failures by exact name - a grep -v PeerLatch hid it.