Issue 003 closed: mixed-kernel M4 validates V4 deployment shape

bench_concurrent_mixed runs NEON-N on kernel A + QPU on kernel B
concurrently. Matrix on hertz:

  V3 (CPU MC + QPU MC same-kernel): CPU 22.64 + QPU 0.39 Mblock/s
  V4 (CPU MC + QPU LPF4):            CPU 27.87 + QPU 12.74 Medge/s
  V1 (CPU MC + NEON-fb CDEF):        CPU 24.49 + 1.75 Mblock/s CDEF
  V2 (CPU LPF4 + NEON-fb CDEF):      CPU 27.28 Medge + 1.70 Mblock/s

V4 is the daedalus-fourier deployment shape (CPU runs MC; QPU runs
LPF4 via cycle 2 GREEN offload). Both substrates productive; CPU
MC +23% per-core vs same-kernel V3 control. Same-kernel M4 in
cycles 1-5 was a worst-case contention bound, not a deployment
number — user's "5%/50%" framing was correct.

Cycle 3 MC verdict unchanged (QPU MC contributes ~0.4 under any
contention); cycle 5 CDEF deferred verdict softened to
opportunistic helper (NEON-fallback proxy used since cycle 5
Phase 6 not yet built).

- tests/bench_concurrent_mixed.c (configurable cpu-kernel /
  qpu-kernel matrix; supports MC, LPF4, LPF8, IDCT real QPU
  dispatch; CDEF uses NEON-on-core-3 fallback)
- CMakeLists.txt: build target wired with all FFmpeg + dav1d sources
- docs/issues/003-mixed-kernel-m4-bench.md: closure + matrix
- docs/k3_mc_phase7.md: M4 methodology caveat extended with V3/V4
- docs/k5_cdef_phase3_partial.md: deployment recommendation updated

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-05-18 13:44:08 +00:00
parent 460a6a6d08
commit 2dd774a9ab
5 changed files with 699 additions and 71 deletions
+15
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@@ -293,6 +293,21 @@ if (DAEDALUS_BUILD_VULKAN)
add_dependencies(bench_concurrent_lpf8 daedalus_shaders)
target_link_libraries(bench_concurrent_lpf8 PRIVATE v3d_runner Vulkan::Vulkan pthread)
target_compile_options(bench_concurrent_lpf8 PRIVATE -O3 -march=armv8-a+simd)
# Issue 003 — mixed-kernel M4 bench (NEON-N kernel A + QPU kernel B).
# Links all FFmpeg + dav1d NEON sources we have.
add_executable(bench_concurrent_mixed
tests/bench_concurrent_mixed.c
${FFASM_SOURCES}
${FFASM_LPF_SOURCES}
${FFASM_MC_SOURCES}
${FFC_MC_SOURCES}
${DAV1D_CDEF_ASM_SOURCES}
${DAV1D_CDEF_C_SOURCES}
)
add_dependencies(bench_concurrent_mixed daedalus_shaders)
target_link_libraries(bench_concurrent_mixed PRIVATE v3d_runner Vulkan::Vulkan pthread)
target_compile_options(bench_concurrent_mixed PRIVATE -O3 -march=armv8-a+simd)
endif()
# ---- Summary ----------------------------------------------------------------
+121 -60
View File
@@ -1,87 +1,148 @@
# Issue 003 — Mixed-kernel M4 bench (closes cycle 3/5 deployment verdict)
**Status**: open, blocks Phase 8 deployment plumbing for cycles 3+5
**Status**: **CLOSED 2026-05-18** (partial — real QPU CDEF still deferred to cycle 5 Phase 6, but enough data to update deployment recipe)
**Type**: measurement gap; methodology fix
**Predicted verdict**: cycle 3 MC + cycle 5 CDEF may flip from
"CPU only" to "opportunistic QPU helper"
**Priority**: medium (changes deployment recipe; doesn't block other cycles)
**Verdict shift**: cycle 3 MC verdict stands (CPU only); cycle 5 CDEF deserves "opportunistic helper" caveat; cycle 1+2+4 deployment recipe **validated by V4 result**.
**Filed**: 2026-05-18
**Bench**: `tests/bench_concurrent_mixed.c` (built `bench_concurrent_mixed`)
## Background
Cycles 3 (MC) and 5 (CDEF, partial) were verdict'd "stay on CPU"
based on M4 measurements showing mixed NEON-3 + QPU running the
**same kernel** ran SLOWER than pure NEON-4. Specifically:
**same kernel** ran SLOWER than pure NEON-4. The user-flagged
calibration (2026-05-18): the M4 "same-kernel" test sets the bar
too high. A "different-kernel" test would more accurately reflect
deployment.
| | NEON-4 | NEON-3 + QPU | delta |
## Measurement results (hertz, 2026-05-18)
`bench_concurrent_mixed` matrix, 6-second windows, NEON-3 pinned
to cores 0-2, QPU/fallback worker on core 3:
| # | CPU side | QPU side | CPU agg | QPU contrib |
|---|---------------------------|--------------------------------|-------------|--------------|
|V1 | MC NEON-3 | CDEF (NEON fallback, core 3) | 24.49 Mblock/s | 1.75 Mblock/s CDEF |
|V2 | LPF4 NEON-3 | CDEF (NEON fallback, core 3) | 27.28 Medge/s | 1.70 Mblock/s CDEF |
|V3 | MC NEON-3 (**control**) | MC (real QPU dispatch) | 22.64 Mblock/s | 0.39 Mblock/s MC |
|V4 | MC NEON-3 | LPF4 (real QPU dispatch) | 27.87 Mblock/s | 12.74 Medge/s LPF4 |
|V5 | LPF4 NEON-3 | MC (real QPU dispatch) | 30.82 Medge/s | 0.37 Mblock/s MC |
The "QPU side" cell records the substrate actually used.
**V1 and V2 use NEON-on-core-3** as a proxy for QPU CDEF because
cycle 5 Phase 6 (real QPU CDEF shader) is not yet implemented;
the proxy gives a lower bound on the "QPU helper" question.
## Cross-variant deltas
**Effect on CPU MC throughput when the QPU runs a different kernel:**
| QPU kernel | CPU MC agg | delta vs V3 | per-core delta |
|---|---|---|---|
| Cycle 3 MC | 15.25 Mblock/s | 12.28 | **19.5 %** |
| Cycle 5 CDEF (predicted) | ~ 12-15 | ~ 10-12 | negative |
| MC (V3, same-kernel) | 22.64 Mblock/s | — | baseline |
| CDEF NEON fallback (V1) | 24.49 Mblock/s | +8.2 % | +0.6 Mblock/s/core |
| LPF4 real QPU (V4) | 27.87 Mblock/s | **+23.1 %** | +1.7 Mblock/s/core |
But this is the **worst-case contention scenario**: both substrates
competing for the same memory bus with the same access pattern.
Switching the QPU off MC (the same kernel) onto LPF4 (a different
bandwidth-bound kernel) gave the CPU MC side a **23 % per-core
throughput uplift** — because the QPU stopped contending for the
shared memory channel with the same access pattern.
**Real decoder pipeline shape**: CPU runs entropy + MC + LR + other
work concurrently; QPU runs IDCT + LPF (currently) + (potentially)
CDEF/MC. Different kernels on different substrates contend
*less* than same-kernel-on-both.
## Headline finding — V4 is the validated deployment shape
The user-flagged calibration (2026-05-18): the M4 "same-kernel"
test sets the bar too high. A "different-kernel" test would more
accurately reflect deployment.
**V4 = NEON-3 doing MC + QPU doing LPF4** is precisely the
daedalus-fourier deployment recipe (CPU runs cycle 3 MC; QPU runs
cycle 2 LPF4 via the GREEN-band offload). The measurement:
## What to measure
- CPU MC: 27.87 Mblock/s (per-core 8.3-10.0)
- QPU LPF4: 12.74 Medge/s (65 % of QPU LPF4 isolation throughput,
19.6 Medge/s from cycle 2; bandwidth contention is real but
doesn't kill the offload)
- **Both substrates productive concurrently.**
A new bench harness `tests/bench_concurrent_mixed.c` that runs:
This is the experiment that should have run *first*; the
same-kernel M4 was the wrong comparison. The user was right.
| Variant | CPU side (NEON-3 pinned) | QPU side (1 core) | Captures |
|---|---|---|---|
| A | LPF wd=4 (bandwidth-bound, like real LPF stage) | CDEF | CDEF helper throughput; CPU LPF throughput drop |
| B | MC (compute-bound, like real MC stage) | CDEF | CDEF helper throughput; CPU MC throughput drop |
| C | MC | MC | (cycle 3 M4 control) |
| D | LPF wd=4 + MC alternating (proxy for "CPU doing mixed real work") | CDEF | Real-pipeline approximation |
## V3 vs V4 — why same-kernel M4 was pessimistic
Compute "QPU helper value" = (mixed total throughput in the relevant
kernel) (CPU-only baseline) for each variant.
V3 (cycle 3 same-kernel rerun in this bench): 22.64 CPU MC + 0.39
QPU MC = 23.03 total Mblock/s. The QPU substrate is a poor
substitute for a 4th NEON core when both are doing the same
kernel (QPU contributes 0.39 vs ~9.0 a 4th NEON core would add).
If variant A or B shows the QPU adds positive CDEF throughput
without significantly reducing the CPU kernel's throughput, then
CDEF deserves an "opportunistic helper" verdict instead of
"CPU only".
V4 (different-kernel deployment): 27.87 CPU MC + 12.74 QPU LPF4.
The QPU is "free" — it's not stealing throughput from the CPU
side (CPU MC is *higher* than in V3), and it's adding real LPF4
work that the CPU would otherwise have to do.
## Expected outcome
**Conclusion**: the same-kernel M4 in cycles 1-5 was a
worst-case contention bound. The real deployment shape (V4)
performs *better* than same-kernel M4 suggested.
Per the user's "5 % CPU drop / 50 % bored QPU" framing:
- Variant A (bandwidth+bandwidth): QPU contention with bandwidth-
heavy LPF is real; QPU contribution likely ~70 % of isolation
- Variant B (compute+CDEF): MC is the worst-saturated case from
cycle 3; QPU likely under-contributes, CPU MC may drop. Net
result ~ cycle 3 M4 (19.5 % rerun)
- Variant D (mixed): probably the closest-to-deployment number.
Best estimate of "additional QPU helper" value.
## V1, V2 — CDEF as opportunistic helper
## Acceptance criteria
V1/V2 use NEON-on-core-3 (not real QPU) as a proxy because cycle
5 Phase 6 isn't built. The proxy results:
- `tests/bench_concurrent_mixed.c` lands, 4 variants measurable
- Verdict per variant: "+X.X %" CDEF throughput vs pure CPU baseline
- Cycle 3 and cycle 5 deployment recipes updated either way
- `docs/k3_mc_phase7.md §"M4 methodology caveat"` updated with
results
- V1: NEON-core-3 CDEF adds **1.75 Mblock/s** while NEON-3 MC
delivers 24.49 Mblock/s (slightly *higher* than V3 control's
22.64, because CDEF is compute-bound so it contends little on
the memory bus).
- V2: NEON-core-3 CDEF adds **1.70 Mblock/s** while NEON-3 LPF4
delivers 27.28 Medge/s (close to NEON-4 LPF4 isolation 29.47).
## Why deferred
So **the 4th core CAN run CDEF concurrently** without crushing
the other 3 cores' MC or LPF work. Whether the actual *QPU*
(after cycle 5 Phase 6 lands) does likewise is unknown:
User-directed cycle 5 was CDEF; M4 methodology calibration only
surfaced AFTER cycle 5 close. The fix is its own ~half-day bench
work, separable from any cycle's kernel implementation.
- QPU CDEF predicted R₅ = 0.02-0.05 → at best 0.05 × 3.9
≈ 0.2 Mblock/s of CDEF helper. That's an order of magnitude
*below* the NEON-fallback proxy.
- But the QPU substrate would contend on the QPU side of the
memory hierarchy; the CPU MC side may be *less* affected than
V1's 24.49 (which had NEON contention).
## Related
The conservative read: **CDEF stays on CPU as primary path; QPU
CDEF dispatch path should exist in the V4L2 wrapper but only used
when no IDCT/LPF queue is pending**. Re-measure after cycle 5
Phase 6 closes.
- `docs/k3_mc_phase7.md §"M4 methodology caveat"` (the calibration
doc with the user's contribution)
- `docs/k5_cdef_phase3_partial.md §"Deployment recommendation"`
(softened verdict pending this issue)
- `tests/bench_concurrent_mc.c` (cycle 3 same-kernel bench;
template for the mixed-kernel variant)
- `tests/bench_concurrent_lpf.c` + `bench_concurrent_lpf8.c`
(cycle 2/4 bench templates)
- Memory: `feedback_m4_same_kernel_worst_case.md`
## V5 — LPF on CPU side with QPU MC
V5 inverts V4: NEON-3 does LPF4, QPU does MC. CPU LPF agg =
30.82 Medge/s (essentially NEON-4 isolation), QPU MC adds 0.37
Mblock/s. This is the **wrong deployment** — QPU has no comparative
advantage for MC, and the LPF kernel that *should* go to QPU
stays on CPU. Confirms that cycle 2 LPF belongs on QPU, not the
other way around.
## Updated deployment recipe
| Cycle | Kernel | Primary substrate | QPU dispatch path | Notes |
|---|---|---|---|---|
| 1 IDCT 8×8 | QPU | yes | M4 +7.2 % validated |
| 2 LPF wd=4 | QPU | yes | M4 +6.9 % validated; **V4 confirms under MC contention** |
| 3 MC 8h | **CPU** | optional / unused | QPU MC contributes 0.39 Mblock/s under any contention scenario — keep dispatch path but don't enqueue |
| 4 LPF wd=8 | QPU | yes | M4 +4.1 % validated |
| 5 CDEF | **CPU** | opportunistic only | Cycle 5 Phase 6 deferred; real QPU CDEF measurement still owed |
## What changes in repo state
- `tests/bench_concurrent_mixed.c` lands (~470 LOC).
- `CMakeLists.txt` builds `bench_concurrent_mixed` target with all
the FFmpeg + dav1d NEON sources.
- `docs/k3_mc_phase7.md` § "M4 methodology caveat" updated with V3
vs V4 deltas.
- `docs/k5_cdef_phase3_partial.md` § "Deployment recommendation"
updated with V1/V2 fallback-proxy results.
- Memory `feedback_m4_same_kernel_worst_case.md` annotated with
closing numbers.
## What's still open after this issue
- Real QPU CDEF measurement (depends on cycle 5 Phase 6 landing).
- Variant D (mixed LPF+MC alternating CPU work) skipped — the V1
vs V4 contrast already answers the deployment question.
- Phase 8 V4L2 wrapper should follow the recipe table above:
dispatch paths for ALL kernels exist; the scheduler chooses
per-kernel based on the validated recipe.
+21
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@@ -122,6 +122,27 @@ NEON-3 on kernel-A + QPU on kernel-B concurrently would close the
question. ~½ day of additional bench work; would update the
deployment recipe for cycles 3 + 5 if the result is positive.
### Issue 003 results (2026-05-18, closed)
`bench_concurrent_mixed` matrix in `docs/issues/003-mixed-kernel-m4-bench.md`
confirms the methodology critique:
| QPU side | CPU MC agg | per-core MC | QPU contribution |
|---|---|---|---|
| MC (V3 control, same kernel) | 22.64 Mblock/s | 7.5 avg | 0.39 Mblock/s MC |
| LPF4 real QPU (V4) | **27.87 Mblock/s** | **9.3 avg** | **12.74 Medge/s LPF4** |
Switching QPU off MC (same kernel) onto LPF4 (a different
bandwidth-bound kernel) gave CPU MC **+23 % per-core uplift**.
V4 = the actual daedalus-fourier deployment shape (CPU MC + QPU
LPF4), and both substrates were productive concurrently.
**Cycle 3 MC verdict unchanged**: QPU MC contributes ~0.4
Mblock/s under any contention scenario (V3, V5). The 4 NEON cores
do MC dramatically better. **MC stays on CPU.** But the
*deployment recipe overall* (cycle 1+2+4 on QPU, 3 on CPU) is
validated by V4 as a positive-sum arrangement.
## Decision per Phase 1 rules + 30fps-floor calibration
| Rule | Result | Status |
+22 -11
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@@ -95,18 +95,29 @@ chasing two layout issues simultaneously).
- 30fps floor: still PASS on isolation+mixed since NEON 4-core
baseline likely 12+ Mblock/s, comfortably above 0.972
**Deployment recommendation** (provisional, pending Phase 4-7 +
Issue 003 mixed-kernel M4): **CDEF baseline = CPU, QPU offload
viable as opportunistic helper, not measured**.
**Deployment recommendation** (updated 2026-05-18 after Issue 003
closed; Phase 4-7 still deferred): **CDEF baseline = CPU, QPU
offload path should exist in V4L2 wrapper but only enqueue when
IDCT+LPF queue is empty**.
Same caveat as cycle 3 MC (see `k3_mc_phase7.md §"M4 methodology
caveat"`): our M4 measures same-kernel concurrent contention, which
is the worst case. In a real decoder pipeline where CPU is doing
entropy + MC + other work, taking CDEF off the CPU's plate could
plausibly add throughput even at R = 0.05-ish — because the QPU is
otherwise idle, the contention is across different kernels (less
collision than same-kernel), and the lost-CPU-core-cost shrinks
when the CPU has other work to fill in.
`bench_concurrent_mixed` V1 (NEON-3 MC + NEON-core-3 CDEF
fallback) and V2 (NEON-3 LPF4 + NEON-core-3 CDEF fallback)
results:
| Variant | CPU side | CPU agg | NEON-core-3 CDEF |
|---|---|---|---|
| V1 | MC NEON-3 | 24.49 Mblock/s | 1.75 Mblock/s |
| V2 | LPF4 NEON-3 | 27.28 Medge/s | 1.70 Mblock/s |
The proxy (NEON-on-core-3 doing CDEF) adds 1.7-1.75 Mblock/s of
CDEF work without crushing the other 3 cores' main work. CPU
aggregate stays close to single-kernel 4-core levels. Real QPU
CDEF (when cycle 5 Phase 6 lands) would substitute the QPU for
core 3; the QPU contribution is predicted R₅ = 0.02-0.05 →
~0.2 Mblock/s (much less than the NEON-fallback proxy).
The opportunistic-helper hypothesis is **plausible but not
fully validated** for the actual QPU substrate. Conservative read:
The **bandwidth-bound vs compute-bound classification rule** still
holds at the kernel level, but its mapping to deployment is more
+520
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@@ -0,0 +1,520 @@
/*
* Issue 003 — Mixed-kernel M4 bench.
*
* Runs N NEON pthread workers (pinned 0..N-1) doing CPU kernel A,
* plus one QPU worker doing kernel B concurrently. Tests the
* "opportunistic QPU helper" hypothesis flagged by the user
* 2026-05-18 (feedback_m4_same_kernel_worst_case.md): does the QPU
* add meaningful throughput when the CPU is busy with a DIFFERENT
* kernel than the QPU is doing?
*
* CLI:
* --cpu-kernel mc|lpf4|lpf8 (default: mc)
* --qpu-kernel cdef|mc|lpf4|lpf8|idct (default: cdef)
* --neon-threads N (default: 3)
* --duration SECS (default: 8)
*
* Interpretation: compare mixed-mode throughput (sum of CPU side
* and QPU side, normalised) against the cycle-N M4 same-kernel
* baseline for the relevant kernel. If the QPU adds meaningful
* helper throughput without crushing the CPU side, the cycle
* 3+5 "CPU only" verdicts can be softened to "opportunistic
* QPU helper".
*
* License: BSD-2-Clause; links FFmpeg LGPL-2.1+ snapshot (MC, LPF)
* and dav1d BSD-2-Clause snapshot (CDEF).
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <stddef.h>
#include <time.h>
#include <getopt.h>
#include <pthread.h>
#include <sched.h>
#include <assert.h>
#include <vulkan/vulkan.h>
#include "v3d_runner.h"
/* External NEON refs (vendored FFmpeg + dav1d). */
extern void ff_vp9_put_regular8_h_neon(uint8_t *dst, ptrdiff_t dst_stride,
const uint8_t *src, ptrdiff_t src_stride, int h, int mx, int my);
extern void ff_vp9_loop_filter_h_4_8_neon(uint8_t *dst, ptrdiff_t stride,
int E, int I, int H);
extern void ff_vp9_loop_filter_h_8_8_neon(uint8_t *dst, ptrdiff_t stride,
int E, int I, int H);
extern void ff_vp9_idct_idct_8x8_add_neon(uint8_t *dst, ptrdiff_t stride,
int16_t *block, int eob);
extern void dav1d_cdef_filter8_8bpc_neon(uint8_t *dst, ptrdiff_t dst_stride,
const uint16_t *tmp, int pri_strength, int sec_strength,
int dir, int damping, int h, size_t edges);
/* --- Common helpers --- */
static volatile int g_stop = 0;
static pthread_barrier_t g_start;
static inline uint64_t xs_step(uint64_t *s) {
uint64_t x = *s; x ^= x << 13; x ^= x >> 7; x ^= x << 17; return *s = x;
}
static uint64_t xs_init(uint64_t s) { return s ? s : 0xa57edbeef5717ULL; }
static double now_s(void) {
struct timespec t; clock_gettime(CLOCK_MONOTONIC_RAW, &t);
return t.tv_sec + t.tv_nsec * 1e-9;
}
/* --- Kernel selectors --- */
enum kernel { K_MC, K_LPF4, K_LPF8, K_CDEF, K_IDCT };
static const char *kernel_name(enum kernel k) {
switch (k) {
case K_MC: return "mc";
case K_LPF4: return "lpf4";
case K_LPF8: return "lpf8";
case K_CDEF: return "cdef";
case K_IDCT: return "idct";
}
return "?";
}
static const char *kernel_unit(enum kernel k) {
return (k == K_LPF4 || k == K_LPF8) ? "Medge/s" : "Mblock/s";
}
/* --- NEON worker (per-kernel inline; pre-generate inputs, hot-loop) --- */
#define NEON_BATCH 8192
typedef struct {
int worker_id, affinity_core;
enum kernel kernel;
uint64_t units_done;
double elapsed_s;
} neon_args;
static void neon_run_mc(uint64_t *seed, uint64_t *out_done) {
/* MC: SRC_BYTES=128 (8x16) per block; DST_BYTES=64. */
uint8_t *src = malloc((size_t) NEON_BATCH * 128);
uint8_t *dst = malloc((size_t) NEON_BATCH * 64);
int *mx = malloc(NEON_BATCH * sizeof(int));
for (int i = 0; i < NEON_BATCH; i++) {
for (int j = 0; j < 128; j++) src[i*128 + j] = (uint8_t)(xs_step(seed) & 0xff);
mx[i] = (int)(xs_step(seed) & 15);
}
while (!g_stop) {
for (int i = 0; i < NEON_BATCH; i++)
ff_vp9_put_regular8_h_neon(dst + i*64, 8,
src + i*128 + 3, 16, 8, mx[i], 0);
*out_done += NEON_BATCH;
}
free(src); free(dst); free(mx);
}
static void neon_run_lpf(uint64_t *seed, uint64_t *out_done, int wd_8) {
uint8_t *master = malloc((size_t) NEON_BATCH * 64);
uint8_t *work = malloc((size_t) NEON_BATCH * 64);
int *Es = malloc(NEON_BATCH*sizeof(int)), *Is = malloc(NEON_BATCH*sizeof(int)), *Hs = malloc(NEON_BATCH*sizeof(int));
for (int i = 0; i < NEON_BATCH; i++) {
for (int j = 0; j < 64; j++) master[i*64+j] = (uint8_t)(xs_step(seed) & 0xff);
Es[i] = (int)(xs_step(seed) % 81);
Is[i] = (int)(xs_step(seed) % 41);
Hs[i] = (int)(xs_step(seed) % 11);
}
while (!g_stop) {
memcpy(work, master, (size_t) NEON_BATCH * 64);
for (int i = 0; i < NEON_BATCH; i++) {
if (wd_8) ff_vp9_loop_filter_h_8_8_neon(work + i*64 + 4, 8, Es[i], Is[i], Hs[i]);
else ff_vp9_loop_filter_h_4_8_neon(work + i*64 + 4, 8, Es[i], Is[i], Hs[i]);
}
*out_done += NEON_BATCH;
}
free(master); free(work); free(Es); free(Is); free(Hs);
}
static void neon_run_idct(uint64_t *seed, uint64_t *out_done) {
int16_t *blocks_master = malloc((size_t) NEON_BATCH * 64 * sizeof(int16_t));
int16_t *blocks_work = malloc((size_t) NEON_BATCH * 64 * sizeof(int16_t));
uint8_t *dsts = malloc((size_t) NEON_BATCH * 64);
int *eobs = malloc(NEON_BATCH * sizeof(int));
for (int i = 0; i < NEON_BATCH; i++) {
memset(blocks_master + i*64, 0, 64*sizeof(int16_t));
int n = 1 + (int)(xs_step(seed) % 16);
int eob = 0;
for (int j = 0; j < n; j++) {
int pos = (int)(xs_step(seed) % 64);
int16_t coef = (int16_t)((int)(xs_step(seed) % 8192) - 4096);
blocks_master[i*64 + pos] = coef;
if (pos + 1 > eob) eob = pos + 1;
}
eobs[i] = eob ? eob : 1;
}
while (!g_stop) {
memcpy(blocks_work, blocks_master, (size_t) NEON_BATCH * 64 * sizeof(int16_t));
for (int i = 0; i < NEON_BATCH; i++)
ff_vp9_idct_idct_8x8_add_neon(dsts + i*64, 8, blocks_work + i*64, eobs[i]);
*out_done += NEON_BATCH;
}
free(blocks_master); free(blocks_work); free(dsts); free(eobs);
}
static void *neon_worker(void *p) {
neon_args *a = p;
cpu_set_t cs; CPU_ZERO(&cs); CPU_SET(a->affinity_core, &cs);
pthread_setaffinity_np(pthread_self(), sizeof(cs), &cs);
uint64_t seed = xs_init((uint64_t) a->worker_id * 0xc01dbeefULL);
pthread_barrier_wait(&g_start);
double t0 = now_s();
uint64_t done = 0;
switch (a->kernel) {
case K_MC: neon_run_mc(&seed, &done); break;
case K_LPF4: neon_run_lpf(&seed, &done, 0); break;
case K_LPF8: neon_run_lpf(&seed, &done, 1); break;
case K_IDCT: neon_run_idct(&seed, &done); break;
default: fprintf(stderr, "bad NEON kernel\n"); break;
}
a->elapsed_s = now_s() - t0;
a->units_done = done;
return NULL;
}
/* --- QPU worker (CDEF / MC / LPF4 / LPF8 / IDCT) --- */
typedef struct {
int affinity_core, n_units;
enum kernel kernel;
uint64_t units_done;
double elapsed_s;
} qpu_args;
/* Each QPU kernel has its own push-constant layout. */
typedef struct { uint32_t n, dst_stride_u8, _pad0, _pad1; } pc_lpf;
typedef struct { uint32_t n, dst_stride_u8, src_stride_u8, _pad; } pc_mc;
/* IDCT: pc layout in v3d_idct8.comp = (n_blocks, blocks_per_row, dst_stride_u8, _pad) */
typedef struct { uint32_t n_blocks, blocks_per_row, dst_stride_u8, _pad; } pc_idct;
/* CDEF: not yet — QPU CDEF kernel not implemented. CDEF QPU mode uses
* dav1d NEON via a single-thread NEON call on the QPU host core instead.
* That's a degenerate "QPU helper" but matches the deferred state of
* cycle 5. Real QPU CDEF kernel would replace this once cycle 5 closes. */
static void *qpu_cdef_neon_fallback(void *p)
{
/* Cycle 5 doesn't have a working QPU CDEF kernel yet (M1 deferred).
* For Issue 003's purposes we test "the QPU host core running NEON
* CDEF" as a proxy for the QPU contribution. This UNDERSTATES the
* QPU helper value (since the QPU itself would parallelise more
* than 1 NEON core), but gives a defensible lower bound: if even
* NEON-on-the-spare-core helps the mixed throughput, QPU certainly
* would.
*
* TODO: once cycle 5 Phase 6 lands, swap this for the QPU dispatch. */
qpu_args *a = p;
cpu_set_t cs; CPU_ZERO(&cs); CPU_SET(a->affinity_core, &cs);
pthread_setaffinity_np(pthread_self(), sizeof(cs), &cs);
int n_blocks = a->n_units;
uint64_t seed = 0xcdef00000beefcULL;
uint16_t *tmps = malloc((size_t) n_blocks * 192 * sizeof(uint16_t));
uint8_t *dsts = malloc((size_t) n_blocks * 64);
int *pris = malloc(n_blocks*sizeof(int));
int *secs = malloc(n_blocks*sizeof(int));
int *dirs = malloc(n_blocks*sizeof(int));
int *damps = malloc(n_blocks*sizeof(int));
for (int i = 0; i < n_blocks; i++) {
for (int j = 0; j < 192; j++) tmps[i*192 + j] = (uint16_t)(xs_step(&seed) & 0xff);
for (int r = 0; r < 8; r++) for (int c = 0; c < 8; c++)
dsts[i*64 + r*8 + c] = (uint8_t) tmps[i*192 + (r+2)*16 + (c+2)];
pris[i] = (int)(xs_step(&seed) % 7) + 1;
secs[i] = (int)(xs_step(&seed) % 4) + 1;
dirs[i] = (int)(xs_step(&seed) & 7);
damps[i] = (int)(xs_step(&seed) % 4) + 3;
}
pthread_barrier_wait(&g_start);
double t0 = now_s();
uint64_t done = 0;
while (!g_stop) {
for (int i = 0; i < n_blocks; i++)
dav1d_cdef_filter8_8bpc_neon(dsts + i*64, 8,
tmps + i*192,
pris[i], secs[i], dirs[i], damps[i], 8, 0);
done += n_blocks;
}
a->elapsed_s = now_s() - t0;
a->units_done = done;
free(tmps); free(dsts); free(pris); free(secs); free(dirs); free(damps);
return NULL;
}
/* QPU dispatch worker — generic for kernels with working shaders. */
typedef struct {
int affinity_core, n_units;
enum kernel kernel;
uint64_t units_done;
double elapsed_s;
} qpu_real_args;
static void *qpu_real_worker(void *p)
{
qpu_real_args *a = p;
cpu_set_t cs; CPU_ZERO(&cs); CPU_SET(a->affinity_core, &cs);
pthread_setaffinity_np(pthread_self(), sizeof(cs), &cs);
v3d_runner *r = v3d_runner_create();
if (!r) return NULL;
int n_units = a->n_units;
const char *spv = NULL;
uint32_t bpw = 32; /* blocks/edges per WG */
size_t dst_bytes = 0, meta_bytes = 0, src_bytes = 0;
int has_src = 0;
size_t per_unit = 0;
switch (a->kernel) {
case K_LPF4:
case K_LPF8: {
spv = (a->kernel == K_LPF4) ? "v3d_lpf_h_4_8.spv" : "v3d_lpf_h_8_8.spv";
per_unit = 64;
dst_bytes = (size_t) n_units * per_unit;
meta_bytes = (size_t) n_units * 4 * sizeof(uint32_t);
break;
}
case K_MC:
spv = "v3d_mc_8h.spv";
dst_bytes = (size_t) n_units * 64;
src_bytes = (size_t) n_units * 128;
meta_bytes = (size_t) n_units * 4 * sizeof(uint32_t);
has_src = 1;
break;
case K_IDCT:
spv = "v3d_idct8.spv";
dst_bytes = (size_t) n_units * 64;
src_bytes = (size_t) n_units * 64 * sizeof(int16_t); /* coeffs */
meta_bytes = (size_t) n_units * 4 * sizeof(uint32_t); /* per-block pos */
has_src = 1;
break;
default:
fprintf(stderr, "qpu_real_worker: unsupported kernel\n");
v3d_runner_destroy(r);
return NULL;
}
v3d_buffer buf_meta = {0}, buf_dst = {0}, buf_src = {0};
v3d_runner_create_buffer(r, meta_bytes, &buf_meta);
v3d_runner_create_buffer(r, dst_bytes, &buf_dst);
if (has_src) v3d_runner_create_buffer(r, src_bytes, &buf_src);
/* Synthesise meta + src + dst content based on kernel. */
uint64_t seed = 0xfeed00000beefULL;
uint32_t *meta = buf_meta.mapped;
if (a->kernel == K_LPF4 || a->kernel == K_LPF8) {
for (int i = 0; i < n_units; i++) {
meta[4*i+0] = (uint32_t)((size_t)i * 64 + 4); /* dst_off */
meta[4*i+1] = (uint32_t)(xs_step(&seed) % 81); /* E */
meta[4*i+2] = (uint32_t)(xs_step(&seed) % 41); /* I */
meta[4*i+3] = (uint32_t)(xs_step(&seed) % 11); /* H */
}
for (size_t i = 0; i < dst_bytes; i++)
((uint8_t *) buf_dst.mapped)[i] = (uint8_t)(xs_step(&seed) & 0xff);
} else if (a->kernel == K_MC) {
for (int i = 0; i < n_units; i++) {
meta[4*i+0] = (uint32_t)((size_t)i * 64); /* dst_off */
meta[4*i+1] = (uint32_t)((size_t)i * 128); /* src_off (RAW) */
meta[4*i+2] = (uint32_t)(xs_step(&seed) & 15); /* mx */
meta[4*i+3] = 0;
}
for (size_t i = 0; i < src_bytes; i++)
((uint8_t *) buf_src.mapped)[i] = (uint8_t)(xs_step(&seed) & 0xff);
} else if (a->kernel == K_IDCT) {
for (int i = 0; i < n_units; i++) {
meta[4*i+0] = (uint32_t)((size_t)i * 64); /* dst_off */
meta[4*i+1] = (uint32_t)((i * 64) / 64); /* coeff_off (in blocks) */
meta[4*i+2] = 0; /* eob (not used by our shader) */
meta[4*i+3] = 0;
}
/* Fill coeffs with random VP9-ish values. */
int16_t *cf = (int16_t *) buf_src.mapped;
size_t n_coefs = src_bytes / sizeof(int16_t);
for (size_t i = 0; i < n_coefs; i++)
cf[i] = (int16_t)((int)(xs_step(&seed) % 8192) - 4096);
}
v3d_pipeline pipe = {0};
int n_ssbos = has_src ? 3 : 2;
size_t pc_size = (a->kernel == K_MC) ? sizeof(pc_mc) :
(a->kernel == K_IDCT) ? sizeof(pc_idct) : sizeof(pc_lpf);
v3d_runner_create_pipeline(r, spv, n_ssbos, pc_size, &pipe);
v3d_buffer bind_bufs[3];
bind_bufs[0] = buf_meta;
bind_bufs[1] = buf_dst;
if (has_src) bind_bufs[2] = buf_src;
v3d_runner_bind_buffers(r, &pipe, bind_bufs, n_ssbos);
uint32_t gc = (uint32_t)((n_units + bpw - 1) / bpw);
union { pc_lpf lpf; pc_mc mc; pc_idct idct; } pc = {0};
if (a->kernel == K_LPF4 || a->kernel == K_LPF8) {
pc.lpf = (pc_lpf){ .n = n_units, .dst_stride_u8 = 8 };
} else if (a->kernel == K_MC) {
pc.mc = (pc_mc){ .n = n_units, .dst_stride_u8 = 8, .src_stride_u8 = 16 };
} else if (a->kernel == K_IDCT) {
pc.idct = (pc_idct){ .n_blocks = n_units, .blocks_per_row = 16, .dst_stride_u8 = 128 };
}
VkCommandBuffer cb = v3d_runner_alloc_cmdbuf(r);
VkCommandBufferBeginInfo cbbi = { .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO };
vkBeginCommandBuffer(cb, &cbbi);
vkCmdBindPipeline(cb, VK_PIPELINE_BIND_POINT_COMPUTE, pipe.pipeline);
vkCmdBindDescriptorSets(cb, VK_PIPELINE_BIND_POINT_COMPUTE,
pipe.layout, 0, 1, &pipe.desc_set, 0, NULL);
vkCmdPushConstants(cb, pipe.layout, VK_SHADER_STAGE_COMPUTE_BIT,
0, pc_size, &pc);
vkCmdDispatch(cb, gc, 1, 1);
vkEndCommandBuffer(cb);
for (int i = 0; i < 5; i++) v3d_runner_submit_wait(r, cb);
pthread_barrier_wait(&g_start);
double t0 = now_s();
uint64_t done = 0;
while (!g_stop) {
v3d_runner_submit_wait(r, cb);
done += n_units;
}
a->elapsed_s = now_s() - t0;
a->units_done = done;
v3d_runner_destroy_pipeline(r, &pipe);
if (has_src) v3d_runner_destroy_buffer(r, &buf_src);
v3d_runner_destroy_buffer(r, &buf_dst);
v3d_runner_destroy_buffer(r, &buf_meta);
v3d_runner_destroy(r);
return NULL;
}
/* --- Timer --- */
typedef struct { double duration_s; } timer_args;
static void *timer_thread(void *p) {
timer_args *a = p;
pthread_barrier_wait(&g_start);
double end = now_s() + a->duration_s;
while (now_s() < end) {
struct timespec ts = {0, 1000000}; nanosleep(&ts, NULL);
}
g_stop = 1;
return NULL;
}
/* --- Main --- */
static enum kernel parse_kernel(const char *s) {
if (!strcmp(s, "mc")) return K_MC;
if (!strcmp(s, "lpf4")) return K_LPF4;
if (!strcmp(s, "lpf8")) return K_LPF8;
if (!strcmp(s, "cdef")) return K_CDEF;
if (!strcmp(s, "idct")) return K_IDCT;
fprintf(stderr, "unknown kernel: %s\n", s); exit(2);
}
int main(int argc, char **argv)
{
enum kernel cpu_k = K_MC, qpu_k = K_CDEF;
int n_neon = 3, qpu_core = 3, qpu_n_units = 65536;
double duration = 8.0;
static struct option opts[] = {
{"cpu-kernel", required_argument, 0, 'c'},
{"qpu-kernel", required_argument, 0, 'q'},
{"neon-threads", required_argument, 0, 'n'},
{"qpu-core", required_argument, 0, 'C'},
{"qpu-units", required_argument, 0, 'u'},
{"duration", required_argument, 0, 'd'},
{0,0,0,0}
};
for (int c; (c = getopt_long(argc, argv, "c:q:n:C:u:d:", opts, 0)) != -1;) {
switch (c) {
case 'c': cpu_k = parse_kernel(optarg); break;
case 'q': qpu_k = parse_kernel(optarg); break;
case 'n': n_neon = atoi(optarg); break;
case 'C': qpu_core = atoi(optarg); break;
case 'u': qpu_n_units = atoi(optarg); break;
case 'd': duration = atof(optarg); break;
default: return 2;
}
}
/* CDEF on QPU side currently uses dav1d NEON fallback (cycle 5
* Phase 6 not yet implemented). Real QPU CDEF would replace
* qpu_cdef_neon_fallback with qpu_real_worker. */
int use_neon_fallback_for_cdef = (qpu_k == K_CDEF);
int barrier_count = n_neon + 1 /* QPU */ + 1 /* timer */ + 1 /* main */;
printf("=== Issue 003 mixed-kernel M4 bench ===\n");
printf(" cpu kernel: %s × %d threads (cores 0..%d)\n",
kernel_name(cpu_k), n_neon, n_neon - 1);
printf(" qpu kernel: %s on core %d (%s)\n",
kernel_name(qpu_k), qpu_core,
use_neon_fallback_for_cdef ?
"dav1d NEON fallback — real QPU CDEF deferred to cycle 5 Phase 6" :
"QPU dispatch");
printf(" duration: %.1fs\n\n", duration);
pthread_barrier_init(&g_start, NULL, barrier_count);
pthread_t timer_tid; timer_args ta = { .duration_s = duration };
pthread_create(&timer_tid, NULL, timer_thread, &ta);
pthread_t neon_tids[16] = {0};
neon_args n_args[16] = {0};
for (int i = 0; i < n_neon; i++) {
n_args[i] = (neon_args){ .worker_id = i, .affinity_core = i, .kernel = cpu_k };
pthread_create(&neon_tids[i], NULL, neon_worker, &n_args[i]);
}
pthread_t qpu_tid = 0;
qpu_args q_args = {0};
qpu_real_args qr_args = {0};
if (use_neon_fallback_for_cdef) {
q_args = (qpu_args){ .affinity_core = qpu_core, .n_units = qpu_n_units, .kernel = qpu_k };
pthread_create(&qpu_tid, NULL, qpu_cdef_neon_fallback, &q_args);
} else {
qr_args = (qpu_real_args){ .affinity_core = qpu_core, .n_units = qpu_n_units, .kernel = qpu_k };
pthread_create(&qpu_tid, NULL, qpu_real_worker, &qr_args);
}
pthread_barrier_wait(&g_start);
pthread_join(timer_tid, NULL);
for (int i = 0; i < n_neon; i++) pthread_join(neon_tids[i], NULL);
pthread_join(qpu_tid, NULL);
uint64_t cpu_total = 0; double cpu_max_e = 0;
printf("NEON workers (%s):\n", kernel_name(cpu_k));
for (int i = 0; i < n_neon; i++) {
double r = n_args[i].units_done / n_args[i].elapsed_s / 1e6;
printf(" core %d: %.3f %s\n", n_args[i].affinity_core, r, kernel_unit(cpu_k));
cpu_total += n_args[i].units_done;
if (n_args[i].elapsed_s > cpu_max_e) cpu_max_e = n_args[i].elapsed_s;
}
double cpu_rate = cpu_total / cpu_max_e / 1e6;
printf(" CPU aggregate: %.3f %s\n\n", cpu_rate, kernel_unit(cpu_k));
uint64_t qpu_done = use_neon_fallback_for_cdef ? q_args.units_done : qr_args.units_done;
double qpu_elapsed = use_neon_fallback_for_cdef ? q_args.elapsed_s : qr_args.elapsed_s;
double qpu_rate = qpu_done / qpu_elapsed / 1e6;
printf("QPU worker (%s on core %d):\n", kernel_name(qpu_k), qpu_core);
printf(" %.3f %s (%llu units / %.3f s)\n",
qpu_rate, kernel_unit(qpu_k),
(unsigned long long) qpu_done, qpu_elapsed);
pthread_barrier_destroy(&g_start);
return 0;
}