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composable_kernel/assets/bank_rules_interactive.html
root 393ebc1a50 WIP backup: snapshot all local notes, slides, tutorials, and kernel work 
Backup commit grouping all in-progress local work so nothing is lost:

- Modified CK-UA kernel + example sources (unified_attention.cpp,
  unified_attention_kernel.hpp) and CMake/build files.
- Updated dispatcher README and ctypes_utils.py.
- New unified_attention example notes: PARAMETERS.md, VARIABLES.md.
- New unified_attention instances for d128 fp16/bf16 (mask/nmask, gqa6).
- New 99_toy_tutorial/ collection: bank-conflict investigations
  (test_*.cpp, *.js, *.gdb, *.asm, *.md), tile distribution / row
  reduction / calling_gemm / thread_buffer tutorials.
- Slide decks and supporting assets (bank_conflict_slides.qmd/.html,
  tile_distribution_slides.qmd, assets/, *_files/, step1_reshape_only,
  xor_full_steps_simple).
- GDB helper script (break_on_ds_read.gdb).

Not intended for upstream review; pure WIP snapshot.
2026-05-11 20:34:52 +00:00

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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>LDS Bank Conflict Rules on CDNA</title>
<style>
:root {
--bg: #0e1329;
--panel: #161d3a;
--text: #eef2ff;
--muted: #a5b0da;
--accent: #6ee7ff;
--ok: #2ecc71;
--broadcast: #3498db;
--bad: #e74c3c;
}
* { box-sizing: border-box; }
body {
margin: 0; padding: 16px;
font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
background: radial-gradient(circle at 20% 0%, #1a2452, var(--bg) 35%);
color: var(--text);
}
.wrap { max-width: 1900px; margin: 0 auto; }
.panel {
background: var(--panel);
border: 1px solid rgba(255, 255, 255, 0.12);
border-radius: 10px;
padding: 12px;
margin-bottom: 12px;
}
h1 { margin: 0 0 8px; font-size: 20px; }
p { margin: 0 0 6px; color: var(--muted); }
.controls { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
button {
background: #253164; color: var(--text);
border: 1px solid #3f4f90; border-radius: 6px;
padding: 6px 10px; cursor: pointer;
}
button.active { background: #3f55a8; border-color: #6fe7ff; }
button:hover { background: #2d3a75; }
.status { margin-left: 8px; color: var(--accent); font-weight: 600; }
.formula { margin-top: 4px; color: #9ef7c9; font-size: 13px; white-space: pre-wrap; }
.gridWrap {
overflow: auto; border: 1px solid rgba(255, 255, 255, 0.1);
border-radius: 8px; background: #101633; padding: 10px;
max-height: 74vh;
}
.legend { display: flex; gap: 14px; align-items: center; font-size: 12px; color: #c8d4ff; margin-bottom: 6px; }
.chip { display: inline-block; width: 14px; height: 14px; border-radius: 3px; margin-right: 4px; border: 1px solid rgba(255,255,255,0.3); vertical-align: middle; }
.cell {
width: 34px; height: 34px;
display: flex; align-items: center; justify-content: center;
font-size: 11px; font-weight: 700; color: #fff;
border: 1px solid rgba(255,255,255,0.2);
}
.hdr { font-size: 10px; color: #9bacde; text-align: center; padding: 2px 0; }
.stats { display:flex; gap:24px; font-size:13px; color:#d8e4ff; margin-top:8px; }
.stats b { color: var(--accent); font-size: 16px; }
</style>
</head>
<body>
<div class="wrap">
<div class="panel">
<h1>LDS Bank Conflict Rules (CDNA, 32 banks x 4 B)</h1>
<p>Each panel below is one <b>half-wave</b>: 32 lanes (rows) x 32 banks (columns).
Colour encodes what happens when the lanes issue one LDS instruction:
<span style="color:var(--ok)">distinct bank</span> = OK,
<span style="color:var(--broadcast)">same bank + same slot</span> = broadcast OK,
<span style="color:var(--bad)">same bank + different slots</span> = N-way conflict.
</p>
<div id="formula" class="formula"></div>
</div>
<div class="panel controls">
<button class="sBtn active" data-s="R1_ok">R1 OK: lane L -> slot L</button>
<button class="sBtn" data-s="R1_broadcast">R1 broadcast: all lanes -> same slot</button>
<button class="sBtn" data-s="R1_fail">R1 FAIL: lane L -> slot 16 L</button>
<button class="sBtn" data-s="R2_ok">R2 OK: fp16 lanes share slot (all same half)</button>
<button class="sBtn" data-s="R2_fail">R2 FAIL: one fp16 dissenter</button>
<button class="sBtn" data-s="R3_step0">R3 b128 sub-step 0</button>
<button class="sBtn" data-s="R3_step1">R3 b128 sub-step 1</button>
<button class="sBtn" data-s="R3_step2">R3 b128 sub-step 2</button>
<button class="sBtn" data-s="R3_step3">R3 b128 sub-step 3</button>
<span id="status" class="status"></span>
</div>
<div class="panel">
<div class="legend">
<span><span class="chip" style="background:var(--ok)"></span>1 lane on this bank (OK)</span>
<span><span class="chip" style="background:var(--broadcast)"></span>N lanes, 1 slot (broadcast OK)</span>
<span><span class="chip" style="background:var(--bad)"></span>N lanes, >1 slot (CONFLICT)</span>
</div>
<div id="gridWrap" class="gridWrap"></div>
<div class="stats">
<span>half-wave size: <b>32</b> lanes</span>
<span>banks: <b>32</b> (gfx942)</span>
<span>conflict ways: <b id="statWays"></b></span>
<span>verdict: <b id="statVerdict"></b></span>
</div>
</div>
</div>
<script>
const HALF = 32;
const NBANKS = 32;
// Each scenario produces a function laneToByteAddr(lane) returning a byte address.
// The visualiser computes slot, bank, and groups lanes per bank.
const scenarios = {
R1_ok: {
title: "R1 OK: stride 4 B per lane (contiguous b32)",
desc:
`lane L addr = L * 4 bytes
slot(L) = L
bank(L) = L % 32
-> 32 distinct banks, each 1 lane. PASS.`,
addr: (l) => l * 4,
},
R1_broadcast: {
title: "R1 broadcast: every lane reads the same 4 B slot",
desc:
`lane L addr = 20 bytes (constant)
slot(L) = 5
bank(L) = 5
-> all 32 lanes on bank 5 slot 5; hardware broadcasts one value. PASS.`,
addr: (_) => 20,
},
R1_fail: {
title: "R1 FAIL: stride 64 B per lane (column of 64 B rows)",
desc:
`lane L addr = L * 64 bytes
slot(L) = L * 16
bank(L) = (L * 16) % 32 in {0, 16}
-> 16 lanes on bank 0 at 16 distinct slots
-> 16 lanes on bank 16 at 16 distinct slots
-> 16-way bank conflict per half-wave. FAIL.`,
addr: (l) => l * 64,
},
R2_ok: {
title: "R2 OK: 8 fp16 lanes share one 4 B slot (all target lo half)",
desc:
`8 lanes ask for the same fp16 element at address 20 bytes.
All 8 map to bank=5, slot=5, fp16 half = lo.
Hardware broadcasts. PASS.
(Remaining 24 lanes are idle / outside this half-wave.)`,
addr: (l) => (l < 8 ? 20 : null),
},
R2_fail: {
title: "R2 FAIL: 7 lanes on lo fp16, 1 lane on hi fp16",
desc:
`8 lanes on bank=5 slot=5, but lane 7 wants the hi fp16 half (addr = 22).
Hardware cannot broadcast two different values in one cycle.
-> full 2-way conflict (degrades the whole group).
Lesson: broadcast is all-or-nothing.`,
addr: (l) => (l < 7 ? 20 : (l === 7 ? 22 : null)),
},
R3_step0: {
title: "R3 ds_read_b128 sub-step 0 of 4",
desc:
`One ds_read_b128 = 16 B / lane = 4 sub-steps of 4 B each.
Sub-step s checks bank/slot at lane_addr + s*4.
Here: contiguous b128, addr(L) = L*16 + 0.
All sub-steps give 32 distinct banks -> wide reads are SAFE only because the
underlying stride pattern already passes R1.`,
addr: (l) => l * 16 + 0,
},
R3_step1: {
title: "R3 ds_read_b128 sub-step 1 of 4",
desc: `addr(L) = L*16 + 4. Same pattern, shifted by 4 B. PASS.`,
addr: (l) => l * 16 + 4,
},
R3_step2: {
title: "R3 ds_read_b128 sub-step 2 of 4",
desc: `addr(L) = L*16 + 8. Same pattern, shifted by 8 B. PASS.`,
addr: (l) => l * 16 + 8,
},
R3_step3: {
title: "R3 ds_read_b128 sub-step 3 of 4",
desc: `addr(L) = L*16 + 12. Same pattern, shifted by 12 B. PASS.`,
addr: (l) => l * 16 + 12,
},
};
const dom = {
status: document.getElementById("status"),
formula: document.getElementById("formula"),
wrap: document.getElementById("gridWrap"),
statWays: document.getElementById("statWays"),
statVerdict: document.getElementById("statVerdict"),
};
function render(key) {
const s = scenarios[key];
dom.status.textContent = s.title;
dom.formula.textContent = s.desc;
// Compute bank assignments for 32 lanes.
// laneAddr[l] = null means lane idle (ignored).
const laneAddr = [];
for (let l = 0; l < HALF; l += 1) laneAddr.push(s.addr(l));
// Group lanes by bank.
const byBank = new Map(); // bank -> Map(slot -> [lanes])
for (let l = 0; l < HALF; l += 1) {
const a = laneAddr[l];
if (a === null) continue;
const slot = Math.floor(a / 4);
const bank = slot % NBANKS;
if (!byBank.has(bank)) byBank.set(bank, new Map());
const slotMap = byBank.get(bank);
if (!slotMap.has(slot)) slotMap.set(slot, []);
slotMap.get(slot).push(l);
}
// Per-bank verdict
let maxWays = 1;
let conflict = false;
const bankState = new Map();
for (const [bank, slotMap] of byBank) {
const lanes = [...slotMap.values()].flat();
if (lanes.length === 1) {
bankState.set(bank, {color: "#2ecc71", label: "L" + lanes[0], tip: `bank ${bank}, slot ${[...slotMap.keys()][0]}`});
} else if (slotMap.size === 1) {
bankState.set(bank, {color: "#3498db", label: lanes.length + "x broadcast", tip: `${lanes.length} lanes -> bank ${bank}, slot ${[...slotMap.keys()][0]} (OK)`});
} else {
bankState.set(bank, {color: "#e74c3c", label: slotMap.size + "-way", tip: `${lanes.length} lanes on bank ${bank} across ${slotMap.size} distinct slots`});
maxWays = Math.max(maxWays, slotMap.size);
conflict = true;
}
}
dom.statWays.textContent = conflict ? maxWays : "0 (no conflict)";
dom.statVerdict.innerHTML = conflict
? `<span style="color:#e74c3c">FAIL</span>`
: `<span style="color:#2ecc71">PASS</span>`;
// Draw: rows = banks (0..31), one row shows the bank's verdict; additionally
// draw a lane-level half-wave strip below showing which bank each lane hit.
dom.wrap.innerHTML = "";
const title = document.createElement("div");
title.style.color = "#b8c8ff";
title.style.fontSize = "13px";
title.style.marginBottom = "6px";
title.textContent = "Bank verdict (32 banks x up-to-N lane collisions)";
dom.wrap.append(title);
// Row 1: one cell per bank with its colour+label.
const bankRow = document.createElement("div");
bankRow.style.display = "grid";
bankRow.style.gridTemplateColumns = `80px repeat(${NBANKS}, 34px)`;
bankRow.style.gap = "2px";
const bl = document.createElement("div");
bl.className = "hdr";
bl.style.textAlign = "right";
bl.style.paddingRight = "4px";
bl.textContent = "bank ->";
bankRow.append(bl);
for (let b = 0; b < NBANKS; b += 1) {
const h = document.createElement("div");
h.className = "hdr";
h.textContent = b;
bankRow.append(h);
}
const lbl = document.createElement("div");
lbl.className = "hdr";
lbl.style.textAlign = "right";
lbl.style.paddingRight = "4px";
lbl.textContent = "verdict";
bankRow.append(lbl);
for (let b = 0; b < NBANKS; b += 1) {
const cell = document.createElement("div");
cell.className = "cell";
const state = bankState.get(b);
if (state) {
cell.style.background = state.color;
cell.title = state.tip;
cell.textContent = state.label.length > 7 ? state.label.slice(0,6)+"." : state.label;
} else {
cell.style.background = "#253164";
cell.style.borderStyle = "dashed";
cell.title = `bank ${b}: no lane`;
}
bankRow.append(cell);
}
dom.wrap.append(bankRow);
// Row 2: lane-level strip (32 lanes).
const laneTitle = document.createElement("div");
laneTitle.style.margin = "14px 0 6px";
laneTitle.style.color = "#b8c8ff";
laneTitle.style.fontSize = "13px";
laneTitle.textContent = "Per-lane view: which bank/slot did lane L land on?";
dom.wrap.append(laneTitle);
const laneRow = document.createElement("div");
laneRow.style.display = "grid";
laneRow.style.gridTemplateColumns = `80px repeat(${HALF}, 34px)`;
laneRow.style.gap = "2px";
const lh = document.createElement("div");
lh.className = "hdr";
lh.style.textAlign = "right";
lh.style.paddingRight = "4px";
lh.textContent = "lane ->";
laneRow.append(lh);
for (let l = 0; l < HALF; l += 1) {
const h = document.createElement("div");
h.className = "hdr";
h.textContent = l;
laneRow.append(h);
}
const lh2 = document.createElement("div");
lh2.className = "hdr";
lh2.style.textAlign = "right";
lh2.style.paddingRight = "4px";
lh2.textContent = "bank@slot";
laneRow.append(lh2);
for (let l = 0; l < HALF; l += 1) {
const cell = document.createElement("div");
cell.className = "cell";
const a = laneAddr[l];
if (a === null) {
cell.style.background = "#253164";
cell.style.borderStyle = "dashed";
cell.textContent = "-";
cell.title = `lane ${l} idle`;
} else {
const slot = Math.floor(a / 4);
const bank = slot % NBANKS;
const state = bankState.get(bank);
cell.style.background = state ? state.color : "#2ecc71";
cell.textContent = `${bank}@${slot}`;
cell.style.fontSize = "9px";
cell.title = `lane ${l}: addr=${a} B, bank=${bank}, slot=${slot}`;
}
laneRow.append(cell);
}
dom.wrap.append(laneRow);
}
function setActive(key) {
for (const b of document.querySelectorAll(".sBtn"))
b.classList.toggle("active", b.dataset.s === key);
}
for (const b of document.querySelectorAll(".sBtn")) {
b.addEventListener("click", () => { setActive(b.dataset.s); render(b.dataset.s); });
}
render("R1_ok");
</script>
</body>
</html>
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