Frank
1a6a78ef73
The 2026-10-12 23:17 power failure reset /sys/module/ttm/parameters/pages_limit from the manual 2026-10-05 raise (200 GiB) back to the kernel default (half of RAM = 125,988 MiB), below the pinned-RAM ledger floor of 150,000 MiB. The serve script's preflight named the refusal and exited 1; Restart=always re-ran it 6,919 times over ~20 hours and frank-archon served nobody. scripts/ttm-preflight.sh (sourced by the serve script) now RAISES the knob itself before refusing: the unit is root, the knob is a 0644 root module parameter, and the cap is a runtime knob whose default is half of RAM — so a manual sysfs write is not a repair procedure, it is a countdown to the next reboot. FRANK_ARCHON_TTM_TARGET_MIB=204800 records the host ceiling; the gate re-reads the cap after writing and only then refuses, so a knob the kernel will not move is still a named failure. Shape change (Frank's call): FOUR decode slots x 200,000 tokens with fp8 (quantized) KV. The pool must back seqs x max-model-len, so fp8 is what funds the fourth slot: at bf16 the four slots cost 11,679 MiB of pool and would cut the resident expert slab to 17,441 MiB (-33 %); at fp8 they cost 6,601 MiB, so the pool stays 6,912 MiB (predicts 843,566 tokens), the VRAM pair stays at the measured 29,120 MiB/card ceiling, the weights slab and the 44 GiB host pool are untouched, and the fused TP all-reduce rides 4 x (1+2) = 12 rows, inside the 25-row bound where the wht6 wire is bit-exact.
77 lines
3.8 KiB
Bash
Executable File
77 lines
3.8 KiB
Bash
Executable File
#!/usr/bin/env bash
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# ttm-preflight.sh — the TTM pages-cap gate for engines that PIN host RAM.
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#
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# Sourced, never executed. An engine that pins tens of GiB of host RAM (the
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# radiance expert pools + the PLE n-gram table) has its pinned pages charged
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# against the kernel's ttm page cap: /sys/module/ttm/parameters/pages_limit
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# (and pages_max on kernels that expose one). The cap function below takes the
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# MIN over the knobs the running kernel actually exposes — an absent knob is
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# skipped, never read as zero, because a zero would refuse a healthy cap.
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#
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# THE LAW THIS FILE EXISTS FOR: the cap is a RUNTIME knob. The kernel default is
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# half of RAM, so every raise is lost on reboot. On 2026-10-12 23:17 a power
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# failure on dankserver reset it 200 GiB -> 125,988 MiB, and frank-archon's
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# preflight refused the start — 6,919 crash-restarts over ~20 hours, with
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# `Restart=always` cheerfully re-running a refusal. A manual sysfs write is
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# therefore not an acceptable repair procedure: the gate raises the knob itself
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# (the units that need it run as root, and the knob is a 0644 root-owned module
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# parameter), re-reads, and only then refuses.
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#
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# Contract (set by the sourcing script's env file):
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# FRANK_ARCHON_TTM_MIN_MIB floor the pinned ledger needs; refuse below it
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# FRANK_ARCHON_TTM_TARGET_MIB value to raise the cap to when it is below the
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# floor (the recorded host ceiling — writing the
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# floor itself would leave the ledger no slack)
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# FRANK_ARCHON_TTM_SYS_DIR knob directory; defaults to the real sysfs
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# path, a test points it at a temp dir.
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# Pages are 4 KiB: pages = MiB x 256.
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: "${FRANK_ARCHON_TTM_SYS_DIR:=/sys/module/ttm/parameters}"
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# Prints the effective cap in MiB, 0 when no knob is readable.
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ttm_cap_mib() {
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local p v cur=""
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for p in "$FRANK_ARCHON_TTM_SYS_DIR/pages_limit" \
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"$FRANK_ARCHON_TTM_SYS_DIR/pages_max"; do
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[ -r "$p" ] || continue
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v="$(cat "$p" 2>/dev/null)" || continue
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[ -n "$v" ] || continue
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v=$(( v * 4 / 1024 ))
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if [ "$v" -lt "${cur:-999999999}" ]; then cur=$v; fi
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done
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echo "${cur:-0}"
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}
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# Writes $1 MiB (as 4 KiB pages) into every writable knob present. Failures are
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# swallowed: the caller re-reads the cap, and a write the kernel refused shows
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# up there (ttm refuses a limit below the pages it has already pinned).
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ttm_raise_cap() {
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local pages=$(( $1 * 256 )) p
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for p in "$FRANK_ARCHON_TTM_SYS_DIR/pages_limit" \
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"$FRANK_ARCHON_TTM_SYS_DIR/pages_max"; do
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if [ -w "$p" ]; then
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echo "$pages" > "$p" 2>/dev/null || true
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fi
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done
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}
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# Returns 0 when the cap clears FRANK_ARCHON_TTM_MIN_MIB, raising it first if
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# needed; returns 1 with a named refusal when it cannot be made to.
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ttm_ensure_cap() {
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local cap
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cap="$(ttm_cap_mib)"
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if [ "$cap" -lt "$FRANK_ARCHON_TTM_MIN_MIB" ]; then
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echo "frank-archon: ttm pages cap is ${cap} MiB, below the pinned-ledger" \
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"floor $FRANK_ARCHON_TTM_MIN_MIB — raising the knob to" \
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"$FRANK_ARCHON_TTM_TARGET_MIB MiB ($(( FRANK_ARCHON_TTM_TARGET_MIB * 256 )) pages)" >&2
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ttm_raise_cap "$FRANK_ARCHON_TTM_TARGET_MIB"
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cap="$(ttm_cap_mib)"
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fi
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if [ "$cap" -lt "$FRANK_ARCHON_TTM_MIN_MIB" ]; then
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echo "ERROR: ttm pages cap is ${cap} MiB, the pinned ledger needs >= $FRANK_ARCHON_TTM_MIN_MIB" >&2
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echo "frank-archon: raise $FRANK_ARCHON_TTM_SYS_DIR/pages_limit (and pages_max if the kernel exposes one) to >= $(( FRANK_ARCHON_TTM_MIN_MIB * 256 )) in 4 KiB pages; a read-only knob needs the module option (options ttm pages_limit=N) and a reboot" >&2
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return 1
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fi
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echo "frank-archon: ttm pages cap ${cap} MiB clears the pinned-ledger floor $FRANK_ARCHON_TTM_MIN_MIB" >&2
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}
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