MobileGL/docs/Disaggregated/notes/perf-p15/SCOREBOARD.md

P15 scoreboard: FCL MC 1.21.5 vanilla at cpuhunt

One row per bench session. MobileGlues (plugin com.fcl.plugin.mobileglues) is the only control measured in every session. Results are reported as fps ratio to MobileGlues. "vs dev" is derived through the fixed dev reference below: vs dev = (arm / MobileGlues) / (dev / MobileGlues).

Targets (PLAN-P15 §0.1):

• Monolith at or above dev, then on par with MobileGlues (ratio 1.00).
• Inproc substantially above MobileGlues.

Dev reference (fixed)

Re-measure only when the scene, clock profile, MC version, FCL build or harness changes.

Measured in session safter (2026-10-08 ~22:00) on harness H2 at cpuhunt (CPU 1.50/1.25 GHz, GPU 903 MHz). All 15 runs were VALID, with no throttling (tpl=0 thr=0) and peak CPU 63 C. dev = 08124c99 (perf-dev worktree, libs/devsym). The table gives 3 interleaved reps per arm; CPU is the GL thread's schedstat time.

arm	fps (r1 / r2 / r3)	mean fps	ratio to MG	CPU ms/frame
MobileGlues	318.8 / 325.1 / 320.5	321.5	1.000	1.70
dev Espryt monolith	297.1 / 277.3 / 281.0	285.1	0.887	2.38
dev Magma monolith	313.8 / 294.5 / 308.4	305.5	0.950	2.01

• vs dev for a session row: Espryt = ratio / 0.887, Magma = ratio / 0.950.
• CPU reference: dev Espryt 2.38 ms/frame (1.40 of MG), dev Magma 2.01 ms/frame (1.18 of MG).
• Dev reps spread more than the other arms (6-7 % vs 1-3 %): dev's warmup needed 2-5 windows to settle where p15s and MobileGlues needed 2. The mean of the three reps is the reference.
• Function-level baseline: one symbolized simpleperf profile per dev backend, taken after the measurement windows in the same runs: runs/safter/dev-Direct{Vulkan,GLES}-r{1,2,3}/perf.data. See MONOLITH-DIFF.md.

Harnesses

• H1 (old probe, through fifi):
  • Not pinned: the scheduler gave MobileGL's monolith render thread the X4 core 72-90 % of the time and MobileGlues' 47-60 %. MobileGlues' fps tracked its X4 share (fifi: 60 % -> 378, 47 % -> 344).
  • fps sources differ by arm: MobileGL arms used the MobileGL fps log before tracing; MobileGlues used the ftrace window.
  • Unfrozen world: daylight cycle on, and time advanced between runs through autosaves.
  • 2 reps per arm.
• H2 (fcl_bench.sh, from safter):
  • FCL is pinned to cpu2-6 (the A720 cluster) after world entry.
  • fps for every arm comes from the SurfaceView BLAST layer's frame number in SurfaceFlinger.
  • The same warmup for every arm: 20 s, then 5 s windows until two consecutive ones agree within 3 %.
  • Measurement: two 5 s windows with no tracer running. Per-thread CPU comes from schedstat over those windows.
  • Frozen save: no daylight, weather or mob-spawn cycle, random ticks off, DayTime 6000.
  • 3 interleaved reps per arm.
  • H2 absolute fps is lower than H1 because nothing runs on X4. Compare H2 rows only with H2 rows.

Sessions

Each cell is the fps ratio to MobileGlues, with presenting-thread CPU in ms/frame in brackets.

• Monolith: the CPU is the GL thread.
• Inproc: the CPU is the apply thread (it presents). The H1 rows use the MobileGL fps log's "presenting thread CPU".
• MobileGlues (MG) cells give fps and CPU.
• A dash means the arm was not in that session.

session (2026-10-08)	harness	build	MG fps (cpu)	mono Espryt	mono Magma	inproc Espryt	inproc Magma
hunt2 14:20	H1	p15l ≈ c8a5abe5	335.0 (1.58)	0.80 (2.19)¹	0.79 (2.18)¹	0.87 (1.63)	0.92 (1.60)
apab 14:51	H1	p15m ≈ 500b63ea	328.6 (1.55)	0.86 (2.06)	0.85 (1.96)	0.90 (1.65)	0.91 (1.58)
blab 16:17	H1	p15n/p15o = c07b8c40	354.9 (1.46)	0.84 (2.02)²	-	0.95 (1.58)	0.94 (1.53)
nxab 17:04	H1	p15p = 61b5eb5a	375.5 (1.43)	0.81 (1.95)	0.84 (1.77)	0.93 (1.54)³	0.89 (1.54) / 0.93³
cens 18:09	H1	p15r = e00db8e6	321.9 (1.57)	-	-	0.93 (1.50) / 0.99³	0.96 (1.46) / 0.99³
fifm 20:07	H1	p15s = 0b96a3ef	361.4 (1.48)	0.82 (1.98)	0.84 (1.84)	-	-
fifi 20:47	H1	p15s = 0b96a3ef	361.1 (1.47)	-	-	0.96 (1.37)	0.94 (1.39)

H2 sessions:

• Cells are the fps ratio to MG, then vs dev, then GL-thread CPU in ms/frame.
• Inproc cells add the apply-thread CPU.

session (2026-10-08)	build	MG fps (cpu)	mono Espryt	mono Magma	inproc Espryt	inproc Magma
safter ~22:00	p15s = 0b96a3ef	321.5 (1.70)	0.746 / 0.84 dev (3.18)	0.768 / 0.81 dev (2.91)	-	-
pt ~23:00	p15t = 3def5cb2 (p15s + Magma blit cache); inproc Magma also p15s	319.0 (1.69)	0.755 / 0.85 dev (3.17)	0.787 / 0.83 dev (2.83)	-	p15s 1.019 (1.36 / 1.42); p15t 1.032 (1.37 / 1.39)
c1 ~00:30 (10-09)	t = p15t; u = p15t + cut 1 (in-frame uploads, local)	324.8 (1.69)	-	t 0.782 / 0.82 dev (2.80); u 0.769 / 0.81 dev (2.86)	u 0.997 (1.38 / 1.63)	u 1.011 (1.37 / 1.39)
c1b ~02:10 (10-09)	t = p15t; v = p15t + 1b (coalesced pass barriers, local)	320.9 (1.69)	-	t 0.783 / 0.82 dev (2.85); v 0.789 / 0.83 dev (2.85)	-	v 1.048 (1.34 / 1.345)
c4 ~02:55 (10-09)	v (as c1b); w = v + cut 4 (Espryt surface-size memo, 66e3b2c1)	321.6 (1.70)	v 0.757 / 0.85 dev (3.18); w 0.762 / 0.86 dev (3.05)	-	-	-
c1c2 ~03:30 (10-09)	t = p15t; y = p15t + 1b + 1c (deferred clears) + cut 4	321.3 (1.70)	-	t 0.795 / 0.83 dev (2.83); y 0.785 / 0.82 dev (2.74)⁴	-	t 1.025 (1.35 / 1.41)⁵; y 1.076 (1.33 / 1.24)
fbm ~05:20 (10-09)	y (as c1c2); z = y + FB-state build memo, one entry per target	321.7 (1.70)	y 0.770 / 0.87 dev (3.04); z 0.775 / 0.87 dev (3.04)	y 0.818 / 0.86 dev (2.65); z 0.831 / 0.87 dev (2.65)	-	-
fbm2 ~11:00 (10-09)	y; z (as fbm); h = y + batch h (485dff14 + c85c9439)	319.7 (1.68)	y 0.763 / 0.86 dev (3.03); h 0.768 / 0.87 dev (3.00)	y 0.805 / 0.85 dev (2.68); z 0.798 / 0.84 dev (2.69); h 0.812 / 0.85 dev (2.62)	-	-
lto ~17:30 (10-09)	o = ca0a3b74 + 2a/2b, -Pmobilegl.enableLto=OFF; l = the same, LTO ON (default)	314.1 (1.71)	o 0.794 (2.99); l 0.800 (2.90)	o 0.850 (2.52); l 0.907 (2.36)	-	-
api29 ~19:00-21:30 (10-09)	a26 = 0650608d + e543e289 (default, API 26); a29 = the same tree, -Pmobilegl.androidApi=29 (42922d21); both LTO ON	324.6 (1.67)	a26 0.771 (2.87); a29 0.777 (2.85)	a26 0.874 (2.33); a29 0.910 (2.26)	a26 0.998 (1.27 / 1.53); a29 1.013 (1.22 / 1.50)	a26 1.088 (1.23 / 1.16); a29 1.136 (1.15 / 1.09)
tls ~22:00 (10-09)	b = origin e70925d3 (libs/egc); t = tlshoist d4a00835 (libs/tls1); both LTO, API 26	318.6 (1.67)	b 0.805 (2.84); t 0.812 (2.79)	b 0.878 (2.35); t 0.933 (2.21)	-	-

• pt: the blit view cache gives Magma inproc +1.2 % fps, with apply −0.03 ms/frame.

• c1: cut 1 is within noise (−1.7 % fps, +0.06 ms). It engaged (the mid-frame submit is gone) but saves ≤0.04 ms; see MONOLITH-DIFF.md.

• c1b: neutral in monolith on CPU and on GPU (busy 29 % in both). Barriers fell from 27.5 to 15.5 per frame, but passes only from 12.6 to 11.5.

• c1c2: Magma per frame, from the counting build:

  • passes 11.5 -> 4.3 (dev 4.1);
  • barriers 15.5 -> 9.0 (dev 3.4);
  • Vulkan calls 343.5 (dev 331.6).

  Effect:

  • Monolith GL-thread CPU −0.09 ms/frame (2.83 -> 2.74); fps within noise.
  • Inproc apply thread −0.17 ms/frame (1.41 -> 1.24) and fps +5.0 % (329.5 -> 345.7).
  • GPU busy: monolith 30 -> 27 % (≈1.18 -> 1.07 GPU ms/frame); inproc 35 -> 33 % (≈1.06 -> 0.96).
  • Profile: the glClear entry fell 0.286 -> 0.098 ms/frame. Part of that pass begin moved into draws (DrawArrays +0.07).

  ⁴ y has 2 valid reps: r2 never reached the world after 3 startup deaths (signal 34 during bootstrap, a harness flake also seen on MobileGlues and other builds). ⁵ t inproc r2 is discarded: a host-side binary_cache_builder pulled libraries over adb inside its measurement window.

• fbm2: batch h moves GL CPU by -0.06 ms (Magma) and -0.03 ms (Espryt).

  • Batch h: per-framebuffer FB-state memo, handle hints, per-buffer handle reuse, the cached per-verb gate, and the Magma hash TLS hoist.
  • The Magma before/after profile (render thread, ms/frame, c1c2 y-r1 -> fbm2 h-r1):
    • MGPipeValidateForVerb 0.328 -> 0.282, BuildFramebufferState 0.058 -> 0.023;
    • FindByLifetimeId + Acquire 0.047 -> 0.003, __emutls_get_address 0.079 -> 0.054;
    • GetOrCreatePipeline 0.026 -> 0.013, MGPipeGetResourceOps 0.007 -> 0.002.
  • The H2 effect is about half of the profile sum. Each piece is below the session noise (+-0.05 ms), so the batch is measured as one.

• lto: ThinLTO + -O3 + ICF/gc/no-semantic-interposition (190580f2) takes GL CPU from 2.52 to 2.36 ms on Magma (fps 267 -> 285) and from 2.99 to 2.90 on Espryt. All runs VALID.

  • Both backends load and render in FCL (one screenshot each, runs/lto-shot).
  • Exported GL/EGL/JNI/vk symbols are identical (2973). LTO drops 3323 internal 3rdparty C++ exports.
  • libMobileGLServer.so links and its only libMobileGL import (mobilegl_server_main) is exported.

• api29 (cpuhunt, vanilla 1.21.5 frozen world, 3 interleaved reps, one bench session per rep with the arm order rotated, 27 of 27 runs VALID): API 26 (shipped, emulated TLS) against API 29 (separate artifact, native ELF TLS), the same tree, both LTO ON.

  • Libs: api26 b843b121..., 0 TLSDESC relocs, 98 __emutls_v.* symbols; api29 1f2ec4a0..., 95 TLSDESC relocs, a PT_TLS segment, 3 __emutls_v.* (libc++abi). Both load and render in FCL.

  • fps, mean of 3 (api26 -> api29, ratio) and GL / apply thread CPU ms/frame:

    arm	fps 26	fps 29	29/26	GL cpu 26 -> 29	apply cpu 26 -> 29
    Magma monolith	283.7	295.5	1.041	2.33 -> 2.26 (0.970)	-
    Magma inproc	353.1	368.6	1.044	1.23 -> 1.15 (0.930)	1.16 -> 1.09 (0.945)
    Espryt monolith	250.2	252.2	1.008	2.87 -> 2.85 (0.994)	-
    Espryt inproc	324.0	328.7	1.015	1.27 -> 1.22 (0.966)	1.53 -> 1.50 (0.978)
    MobileGlues (control)	324.6 (1.67 ms)

  • Per-rep fps: Magma mono 277.5 / 291.6 / 282.2 vs 298.5 / 286.2 / 301.9 (rep 2, where api29 ran first, is the one rep it lost by 1.9 %); Magma inproc 351.9 / 354.9 / 352.4 vs 365.3 / 374.6 / 365.9 (api29 ahead in every rep); Espryt mono 251.9 / 249.1 / 249.4 vs 253.6 / 248.0 / 255.1; Espryt inproc 327.1 / 314.9 / 329.9 vs 324.1 / 326.6 / 335.3. Spread (max-min)/mean is 0.8-5.3 %: the Magma inproc gain (+4.4 %, spread 0.8 / 2.5 %) is outside it, Magma monolith (+4.1 %, spread 5 %) is about at it, both Espryt gains are inside it.

  • Device state, every run: CPU 1497 (cpu2-6) / 1248 (cpu0) / 1478 (cpu7) MHz, GPU 903 MHz, samples inside the measure windows only; tpl 0, throttling 0, no "max capped"; peak over the 27 runs CPU 62.8 C, GPU 56.2 C, skin 43.9 C; daemons stopped during a session and restored after (5 running again, max clocks back to stock); swap=false; anland off; FCL pinned to cpu2-6 (taskset 7c); cooldown to battery <= 33.0 C before each session.

  • Simpleperf, one run per cell (monolith render thread, 6 s, cpu-clock 4000 Hz; runs/api29ab-sp). The share of TLS access in the render thread's on-CPU time:

    cell	on-CPU ms/frame	TLS symbol	ms/frame	share
    Magma api26	2.546	__emutls_get_address	0.052	2.1 %
    Magma api29	2.501	tlsdesc_resolver_dynamic (linker64)	0.051	2.1 %
    Espryt api26	3.016	__emutls_get_address	0.058	1.9 %
    Espryt api29	3.259	tlsdesc_resolver_dynamic (linker64)	0.047	1.4 %

  • Reading:

    • API 29 does not remove the TLS cost of the monolith render thread. MobileGL is dlopen'ed, so bionic resolves each TLSDESC through the linker's dynamic resolver (tlsdesc_resolver_dynamic), a call that costs about what __emutls_get_address did (0.05 ms/frame, about 2 % of the thread). The native-TLS switch is therefore not the source of the Magma gain; whatever it is (code layout and codegen of a different link, or the android-29 platform), this A/B does not isolate it.
    • Untested lead for a real TLS saving: a static TLS model (initial-exec) for the hot variables. Bionic's room for static TLS in a dlopen'ed library is limited, so it needs its own measurement.
    • The Espryt monolith profile run read 242.6 / 245.4 fps against 252.2 / 254.0 for api26, opposite to the 3-rep means; it is one run, the 3 interleaved reps decide.

• tls (cpuhunt, 3 interleaved reps, all 15 runs VALID, tpl=0 thr=0, peak CPU 57.7-61.3 C): hot-path TLS cut (tlshoist: constinit pointer slots for pGLContext and gPipeInputs, one-block thread_local caches, inline Magma session read). Emulated-TLS calls per frame (counting build, run tlsdiag): Magma 9111 -> 4336, Espryt 7585 -> 3149.

  • fps r1 / r2 / r3: Magma b 285.6 / 275.4 / 277.8 (279.6), t 295.1 / 301.4 / 295.2 (297.2, +6.3 %); Espryt b 269.5 / 251.9 / 248.4 (256.6), t 260.6 / 270.6 / 245.2 (258.8, +0.9 %); MobileGlues 318.6.
  • GL CPU (schedstat): Magma 2.35 -> 2.21, Espryt 2.84 -> 2.79 ms/frame.
  • __emutls_get_address on the render thread (simpleperf, mean of 3 reps): Magma 0.058 -> 0.034, Espryt 0.049 -> 0.035 ms/frame. Magma's MobileGL-side total falls more than that (-0.04 to -0.20 per rep): the callers lose the init-wrapper/guard calls and spills too.
  • A second session (tlspf, Perfetto, no simpleperf, 12 runs VALID) read Magma 278.6 -> 284.4 fps (CPU 2.40 -> 2.30) and Espryt 246.2 -> 254.5 (2.94 -> 2.83). Traces in runs/tlspf/*/p15.pftrace, not analysed yet.

• bsl3 (gpuhunt, stopped on a CPU max cap in rep 2): r1 Magma 55.6, Espryt 52.8, MobileGlues 57.2 fps. That is Magma 0.97 and Espryt 0.92 of MobileGlues.

• c1cbsl (gpuhunt, Iris + BSL, after a cooldown, 3 reps): 1c does not cost GPU time.

  • VALID runs: t 53.8 / 53.9 fps vs y 55.7 / 55.5 (+3.4 %), all at 100 % GPU busy (18.5 -> 17.9 GPU ms/frame).
  • MobileGlues read 56.2 / 55.7 / 56.1, which puts Magma y at about 0.99 of it. All three MobileGlues runs (and t r2, y r2) are INVALID for one reason: the freq sampler's first sample, about 40 s before the windows, catches the idle GPU at 231 MHz. Every in-window sample of every run is at the 578 MHz pin.
  • A window-scoped validity check (freqcheck over the measure_raw.txt span) would admit them. That is a harness change, not yet made.

• ebbsl (gpuhunt, Iris + BSL, Espryt monolith, 3 reps, one arm per cooldown, all VALID): the two parked Espryt GPU items (native depth glCopyImageSubData, attachment shadow) do not help. Builds: x = origin 9f610167 + the items, b = origin 9f610167, both LTO; MobileGlues is the plugin.

  • fps r1 / r2 / r3: x 51.4 / 51.3 / 51.5 (mean 51.4), b 52.7 / 51.8 / 51.0 (51.9), MobileGlues 56.5 / 55.6 / 55.3 (55.8). Ratio to MobileGlues: x 0.921, b 0.930 (x vs b -1.0 %, noise). Target 0.95 not reached.
  • GPU: busy 100 % in every run; union of kgsl cmdbatch intervals per frame (x / b / MobileGlues) 19.45 / 19.29 / 17.88 ms, 1.04 cmdbatches per frame in all three.
  • Device state: gpuhunt (CPU 2380/1689 MHz, GPU 578 MHz; in-window min = max for every policy), tpl=6 thr=0, peak CPU 75.5-79.4 C, GPU 63.2-65.9 C, skin 42.4-44.5 C, daemons stopped(5), swap=false, anland off.
  • Engagement (one simpleperf run each, render thread): BlitDepthTexture2D 0.100 ms/frame in b, gone in x; Espryt CopyImageSubData 0.115 -> 0.072; SyncToBackendByHandle 0.178 -> 0.162.
  • Vanilla cpuhunt (1500/1250/903 MHz, 3 reps, all VALID, peak CPU 58 C): Espryt monolith GL CPU x 2.87, b 2.83 ms/frame; fps x 249.9 / 251.4 / 244.2 (248.5), b 250.1 / 256.5 / 255.2 (254.0), GPU busy 17 %.
  • Not landed: wip/espryt-depthcopy-measured. The BSL frame is GPU-bound and its GPU time did not move.

• fbm: the first memo is within noise on both backends (CPU 2.65 / 2.65 Magma, 3.04 / 3.04 Espryt).

  • It engaged only partly: Magma BuildFramebufferState 0.058 -> 0.032 ms/frame, and Espryt kept missing.
  • The build only runs on a binding switch, so one entry per target misses on every A/B/A switch. Batch h makes it per framebuffer.
  • Session noise: y Magma r3 read 2.54 against 2.70-2.72 in r1/r2, with nothing in its state to explain it.

• c4: Espryt GL-thread CPU fell 0.13 ms/frame (3.18 -> 3.05 in all three reps); fps moved by less than the noise. The profile confirms it: QueryCurrentSurfaceSize 0.070 -> 0.012 and SyncRenderState 0.092 -> 0.028 ms/frame.

Thread state, Perfetto SQL (c1, H2; pftstate.py over trace_processor_shell v58.2 on the .pftrace taken after the windows; means of 3 reps; ms/frame):

arm	fps	GL run	GL woken-wait	GL preempted	GL sleep	apply run	apply sleep	both on-CPU / neither
MobileGlues monolith	324.8	1.91	0.036	0.030	1.05	-	-	-
Magma monolith (t)	254.1	3.09	0.042	0.027	0.71	-	-	-
Magma monolith (u)	249.8	3.05	0.045	0.045	0.79	-	-	-
Magma inproc (u)	328.3	1.43	0.047	0.073	1.45	1.61	1.31	41 % / 41 %
Espryt inproc (u)	323.8	1.39	0.057	0.088	1.51	1.95	1.02	42 % / 34 %
c1c2: MobileGlues monolith	321.3	1.95	0.039	0.019	1.05	-	-	-
c1c2: Magma monolith (t)	255.3	3.11	0.039	0.038	0.66	-	-	-
c1c2: Magma monolith (y, 1c)	252.3	3.07	0.047	0.029	0.75	-	-	-
c1c2: Magma inproc (t)	329.5	1.38	0.050	0.073	1.48	1.58	1.32	40 % / 42 %
c1c2: Magma inproc (y, 1c)	345.7	1.39	0.043	0.079	1.33	1.43	1.31	39 % / 42 %

The sleeps break down as:

• Monolith (both stacks): the app's waitForever slice inside queueBuffer, woken by kgsl-events, i.e. the GPU fence of the previous frame.
• Inproc GL thread: woken by mgl-srv-apply.
• Inproc apply thread: waitForever (the GPU fence), as in monolith.

The table below is the same window from the ftrace text (threadstate.py). It carries GPU busy, because this Perfetto config does not record the kgsl events.

arm	GL thread on-CPU	preempted	sleeping (main reason)	apply thread on-CPU	apply sleeping	both on-CPU / neither	GPU busy
MobileGlues monolith	61 % (1.88)	0.03	37 %: present fence waitForever 1.13	-	-	-	30 %
Magma monolith (p15t)	78 % (3.08)	0.03	20 %: present fence 0.78	-	-	-	29 %
Magma inproc (u)	47 % (1.42)	0.11	48 %: woken by the apply thread 1.45	52 % (1.59)	present fence 1.30	40 % / 41 %	36 %
Espryt inproc (u)	47 % (1.45)	0.10	48 %: woken by the apply thread 1.47	63 % (1.95)	present fence 1.07	44 % / 34 %	30 %

What the table shows:

• Monolith Magma is CPU-bound: the GL thread is on-CPU 78 % and preemption is negligible.
• MobileGlues finishes its CPU work sooner, then waits on the present fence.
• Inproc is bounded by present-fence latency at credit 1, not by CPU: the apply thread waits on the fence while the GL thread waits on the apply thread, and for 34-41 % of the time neither runs. The GPU is only 30-36 % busy.

Sources:

• .pftrace captures for the Perfetto UI are in runs/c1/*/p15.pftrace.
• The numbers come from the same window's ftrace text via threadstate.py: no trace processor is installed.

H2 spread, measured as (max - min) / mean over the 3 interleaved reps of each arm:

• sbefore (H1 probe, same day, 3 reps): Espryt 288.6 / 287.7 / 315.2 (9.3 %), Magma 298.0 / 295.0 / 312.0 (5.6 %), MobileGlues 370.2 / 374.7 / 375.1 (1.3 %).
• safter (H2): Espryt 240.2 / 240.8 / 237.9 (1.2 %), Magma 245.3 / 251.3 / 244.1 (2.9 %), MobileGlues 2.0 %, dev 6-7 %.
• The X4 core hid part of the gap: on the A720 cluster, p15s is 0.84 (Espryt) and 0.81 (Magma) of dev. In CPU, that is +0.80 and +0.90 ms/frame over dev.

Notes:

1. hunt2 monolith comes from the profiled sub-run (hunt2-prof, simpleperf in the window), so it is not the same sub-session as its MobileGlues control. Dev in that sub-run: Espryt 305.3 (1.64), Magma 302.2 (1.59), that is 0.91 / 0.90 of hunt2's MobileGlues.
2. blab monolith Espryt is p15n (p15o has no monolith arm in blab).
3. Present credit 2 (MOBILEGL_IPC_PRESENT_CREDIT=2); the default credit is 1. The FIF sweep (fifm/fifi, FIF 2/3/4) showed no significant effect; FIF 3 is the default and is the column shown.

H1 spread: two reps of the same arm differ by up to 10 % within a session (fifi MobileGlues 378.4 / 343.8, apab p15m Magma monolith 289.3 / 266.6). MobileGlues ranged from 322 to 376 across sessions. H1 ratios therefore carry roughly ±5 %.

egc: global-constants key (e70925d3) vs 0650608d, monolith, cpuhunt, vanilla frozen world

Baseline b = 0650608d, x = e70925d3 (both LTO-ON, API 26), FCL on cpu2-6, simpleperf on the render thread, 3 interleaved reps per arm, all 12 runs VALID (clocks pinned in the windows, tpl=0 thr=0, daemons stopped, swap off). EmitGlobalConstants is inlined under LTO, so its cost is every sample with an EmitGlobalConstants inline frame (llvm-symbolizer --inlines); ValidateForVerb is inclusive.

backend	arm	fps	GL CPU ms/frame	ValidateForVerb ms/frame	EmitGlobalConstants ms/frame
Magma	b	279.4	2.39	0.190	0.0220 (0.021 / 0.025 / 0.020)
Magma	x	274.6	2.38	0.194	0.0142 (0.016 / 0.013 / 0.013)
Espryt	b	249.6	2.85	0.215	0.0214 (0.022 / 0.020 / 0.022)
Espryt	x	252.8	2.82	0.194	0.0136 (0.013 / 0.014 / 0.014)

EmitGlobalConstants drops by 0.0078 ms/frame on both backends (about 35 %), inside the expected 0.007-0.010. The whole frame (fps, GL CPU, ValidateForVerb) is within noise: ValidateForVerb varies 0.17-0.22 between reps of one arm.