PERF-2 P0: intra-step profiler — StepTimers on the overset solver (RTX_PROFILE; overlap build / predictors / patch BiCGSTAB / background Poisson with its setup-vs-iterate split / round exchange / apply / end exchange), PoissonSolution carries setup_ns and iterate_ns, the harness times advance / restore / snapshot / load sampling / force / FEA predictor and prints the wall split of the coupled phase; no clock is read when profiling is off; the reclassified/step progress denominator fixed (was ×4)

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YJPeT6WA2e7YvAnS875AHL

crates/specialized/rtx-cfd/src/solvers/incompressible/embedded/mod.rs

@@ -41,7 +41,7 @@ mod projection;
 use super::ale::{AleBoundaries, SideBoundary};
 use super::embedded_body::{EmbeddedBody, EmbeddedMask, FaceKind};
 use super::poisson::{
-    solve_multigrid_pcg, MgPrecision, MultigridParameters, PoissonProblem, PoissonSolverKind,
+    MgPrecision, MultigridParameters, PoissonProblem, PoissonSolverKind, solve_multigrid_pcg,
 };
 use super::simple::ConvectionScheme;
 use super::{FlowField, SolverResult};
@@ -168,6 +168,9 @@ pub struct EmbeddedPisoSolver {
     /// (measured: at 1e-2 the first corrector's rounds never settled below
     /// a 1e-3 relative change — 20/20 rounds every step).
     inner_stop_factor: f64,
+    /// PERF-2 P0: Poisson `(setup ns, iterate ns, calls)` summed over
+    /// every multigrid-PCG solve (`docs/perf2_campaign.md`).
+    poisson_profile: std::cell::Cell<(u64, u64, u64)>,
     moving: bool,
     /// Mask hysteresis band in multiples of the min cell size (0 = off).
     mask_hysteresis: f64,
@@ -194,6 +197,7 @@ impl EmbeddedPisoSolver {
             fringe: None,
             fringe_correction: Vec::new(),
             inner_stop_factor: 1e-2,
+            poisson_profile: std::cell::Cell::new((0, 0, 0)),
             moving: false,
             mask_hysteresis: 0.0,
             time: 0.0,
@@ -290,6 +294,11 @@ impl EmbeddedPisoSolver {
     }
 
     /// Relative part of the pressure solve's inner stop (see the field).
+    /// The Poisson solves' `(setup ns, iterate ns, calls)` so far.
+    pub fn poisson_profile(&self) -> (u64, u64, u64) {
+        self.poisson_profile.get()
+    }
+
     pub fn set_inner_stop_factor(&mut self, factor: f64) {
         self.inner_stop_factor = factor;
     }