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#45 ROOT CAUSE + FIX: the gauge executive starves in MP -- panels froze at healthy fps

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Instruments repaint via the background task pump, which authentically runs
ONLY in the frame's leftover time with a floor of ONE pump per frame; the
gauge renderer is 1 of ~7 round-robin tasks and each turn advances ONE gauge
of ~140 active, with the rate mask advancing once per full sweep.  On a busy
MP mission the foreground eats the whole frame budget, the floor becomes the
norm, and the whole instrument stack rotates once in MINUTES at perfect fps:
comms-panel K/D stuck at 0, recharge tickers frozen, while the tallies and
their replication underneath were exactly right.  Measured: 4-node bench at
70-90 fps gave the PilotList ~2 Execute turns in six minutes.

Fix, both env-tunable, authentic behavior restorable:
  BT_BG_MIN      (APPMGR.cpp, default 32, 0=authentic)  minimum background
                 pumps per frame regardless of slack;
  BT_GAUGE_BATCH (GAUGREND.cpp, default 32, 1=authentic) gauges advanced per
                 gauge-renderer turn (a visit is only a rate-mask check
                 unless the gauge is due).
Verified 4-node self-damage bench: sweeps 0.006/s -> 18-20/s, PilotList ~10
Exec/s, ALL FOUR panels tracked every death live (0->11) within ~1s, bg cost
2-4 ms/frame, respawn ledger clean (40 cycles, 0 swallow / 0 mismatch).

Also: BT_PERF now reports gaugeTurns/sweeps/active alongside bgTasks;
BT_AF_PERIOD now throttles the missile autofire group too (unthrottled spam
trips the documented FailureHeat all-weapons brick, which froze run 1 of the
cross-fire bench).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
Joe DiPrima
2026-07-30 11:22:47 -05:00
co-authored by Claude Fable 5
parent bfa1b04990
commit 494f32efb4
5 changed files with 106 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
engine/MUNGA/APPMGR.cpp
+38 -1
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@@ -193,6 +193,33 @@ Background_Loop:
current_application.First();
application = current_application.GetCurrent();
//
// BT MINIMUM BACKGROUND FLOOR (#45 root cause, 2026-07-30). Authentically
// the background tasks run ONLY in the frame's leftover time, with a floor
// of a single pump per frame -- fine on a 1995 pod (one app, designed
// slack), but on a busy MP mission the foreground eats the whole frame
// budget, the floor becomes the norm, and the GAUGE renderer (1 of ~7
// round-robin tasks, ONE gauge advanced per turn) starves: every cockpit
// instrument -- the comms-panel K/D columns, weapon recharge tickers --
// freezes at its last paint while the underlying values (and fps!) stay
// perfectly healthy. Measured: 4-node bench at 70-90 fps gave the
// PilotList ~2 Execute turns in SIX MINUTES. Guarantee a minimum number
// of pumps per frame so a full instrument rotation completes in ~1s
// regardless of slack; the added worst-case cost is bounded and small.
// BT_BG_MIN overrides (0 = authentic slack-only behavior).
//
{
static int s_bgMin = -1;
if (s_bgMin < 0)
{
const char *e = getenv("BT_BG_MIN");
s_bgMin = e ? atoi(e) : 32;
if (s_bgMin < 0) s_bgMin = 0;
if (s_bgMin > 256) s_bgMin = 256;
}
if (backgroundTasksRun < s_bgMin)
goto Background_Loop;
}
if (t2 < end_of_frame)
{
@@ -219,10 +246,20 @@ Background_Loop:
if (Now() - s_lastP >= 1.0f)
{
s_lastP = Now();
// gauge-executive rotation health (#45): turns = one-gauge
// Updates and sweeps = full active-list passes SINCE THE LAST
// PRINT (~1s); active = the instrument roster size. A frozen
// panel shows here as sweeps=0.
extern int gBTGaugeTurns, gBTGaugeSweeps, gBTGaugeActive;
DEBUG_STREAM << "[perf] frame=" << (float)(Now() - beginFrameTimestamp)
<< " fg=" << (float)(startBackground - beginFrameTimestamp)
<< " bg=" << (float)(endBackground - startBackground)
<< " bgTasks=" << backgroundTasksRun << "\n" << std::flush;
<< " bgTasks=" << backgroundTasksRun
<< " gaugeTurns=" << gBTGaugeTurns
<< " sweeps=" << gBTGaugeSweeps
<< " active=" << gBTGaugeActive << "\n" << std::flush;
gBTGaugeTurns = 0;
gBTGaugeSweeps = 0;
}
}
}