PERF-2 P0-b: CG iterations per Poisson solve in the profile (ms per V-cycle) and sub-timers inside the patch regeneration (outline, hull + offset, ring projection, Winslow sweeps, respace, warm bookkeeping, mesh finalisation)

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

crates/specialized/rtx-cfd/src/mesh/patch_gen.rs

@@ -721,6 +721,23 @@ pub fn cylinder_flag_patch_deformed_tip(
 
 /// [`cylinder_flag_patch_deformed_from`] with the flat tip.
 #[allow(clippy::too_many_arguments)]
+thread_local! {
+    /// PERF-2 P0 (`docs/perf2_campaign.md`): wall time [ns] of the
+    /// regeneration's stages on this thread — outline, hull + offset, ring
+    /// projection, Winslow sweeps, respace, warm bookkeeping, mesh
+    /// finalisation — and the number of builds (slot 7).
+    static REGEN_NS: std::cell::RefCell<[u64; 8]> = const { std::cell::RefCell::new([0; 8]) };
+}
+
+fn regen_charge(slot: usize, start: std::time::Instant) {
+    REGEN_NS.with(|r| r.borrow_mut()[slot] += start.elapsed().as_nanos() as u64);
+}
+
+/// The regeneration's stage times so far on this thread (see `REGEN_NS`).
+pub fn regen_profile() -> [u64; 8] {
+    REGEN_NS.with(|r| *r.borrow())
+}
+
 pub fn cylinder_flag_patch_deformed_from_tip(
     prev: Option<&PatchMesh>,
     centre: [f64; 2],
@@ -736,9 +753,11 @@ pub fn cylinder_flag_patch_deformed_from_tip(
     winslow_sweeps: usize,
     tip_corner: f64,
 ) -> CfdResult<(PatchMesh, (usize, f64))> {
+    let t0 = std::time::Instant::now();
     let (inner, tip) = cylinder_flag_outline_deformed_tip(
         centre, r, t, edges, x_tip_ref, fillet, 3, 16, h, 1.15, tip_corner,
     );
+    regen_charge(0, t0);
     // With a flat tip the outline's corners would put 90° corners on the
     // hull, whose normal offset folds the rays at the tip; the tip disc
     // (already a hull source) covers the tip, so the inner points ahead of
@@ -1087,8 +1106,11 @@ fn o_grid_from_outline(
 ) -> CfdResult<(PatchMesh, (usize, f64))> {
     inner.reverse(); // clockwise
     let ns = inner.len();
+    let t0 = std::time::Instant::now();
     let hull = convex_hull(hull_src);
     let outer_poly = offset_convex_polygon(&hull, offset, 24);
+    regen_charge(1, t0);
+    let t0 = std::time::Instant::now();
     // Initial outer ring: the inner point pushed along its outward normal
     // (the ring is clockwise, so the outward normal is the LEFT-hand normal
     // of the direction of travel) and projected onto the hull offset —
@@ -1109,6 +1131,7 @@ fn o_grid_from_outline(
             )
         })
         .collect();
+    regen_charge(2, t0);
     let mut inner_closed = inner.clone();
     inner_closed.push(inner[0]);
     // Transfinite start, or the previous mesh's interior with the new
@@ -1153,15 +1176,23 @@ fn o_grid_from_outline(
         let mut last = f64::INFINITY;
         let mut done = 0;
         for k in 0..winslow_sweeps {
+            let t0 = std::time::Instant::now();
             let before = x.clone();
+            regen_charge(5, t0);
+            let t0 = std::time::Instant::now();
             winslow_smooth(&mut x, ns, 0.0, 1, Some(&outer_poly));
+            regen_charge(3, t0);
+            let t0 = std::time::Instant::now();
             respace_rays(&mut x, ns, &eta);
+            regen_charge(4, t0);
+            let t0 = std::time::Instant::now();
             last = x
                 .iter()
                 .zip(&before)
                 .flat_map(|(r, b)| r.iter().zip(b))
                 .map(|(p, q)| ((p[0] - q[0]).powi(2) + (p[1] - q[1]).powi(2)).sqrt())
                 .fold(0.0, f64::max);
+            regen_charge(5, t0);
             done = k + 1;
             if last < 1e-10 * h {
                 break;
@@ -1169,10 +1200,15 @@ fn o_grid_from_outline(
         }
         (done, last)
     } else {
+        let t0 = std::time::Instant::now();
         let report = winslow_smooth(&mut x, ns, 1e-10 * h, winslow_sweeps, Some(&outer_poly));
+        regen_charge(3, t0);
+        let t0 = std::time::Instant::now();
         respace_rays(&mut x, ns, &eta);
+        regen_charge(4, t0);
         report
     };
+    let t0 = std::time::Instant::now();
     let mut xs = Vec::with_capacity((nn + 1) * (ns + 1));
     let mut ys = Vec::with_capacity(xs.capacity());
     for row in &x {
@@ -1182,5 +1218,7 @@ fn o_grid_from_outline(
         }
     }
     let mesh = PatchMesh::from_nodes(ns, nn, xs, ys, Some([0.0, 0.0]))?;
+    regen_charge(6, t0);
+    REGEN_NS.with(|r| r.borrow_mut()[7] += 1);
     Ok((mesh, report))
 }

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

@@ -168,9 +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)>,
+    /// PERF-2 P0: Poisson `(setup ns, iterate ns, calls, CG iterations)`
+    /// summed over every multigrid-PCG solve (`docs/perf2_campaign.md`).
+    poisson_profile: std::cell::Cell<(u64, u64, u64, u64)>,
     moving: bool,
     /// Mask hysteresis band in multiples of the min cell size (0 = off).
     mask_hysteresis: f64,
@@ -197,7 +197,7 @@ impl EmbeddedPisoSolver {
             fringe: None,
             fringe_correction: Vec::new(),
             inner_stop_factor: 1e-2,
-            poisson_profile: std::cell::Cell::new((0, 0, 0)),
+            poisson_profile: std::cell::Cell::new((0, 0, 0, 0)),
             moving: false,
             mask_hysteresis: 0.0,
             time: 0.0,
@@ -294,8 +294,8 @@ 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) {
+    /// The Poisson solves' `(setup ns, iterate ns, calls, CG iterations)` so far.
+    pub fn poisson_profile(&self) -> (u64, u64, u64, u64) {
         self.poisson_profile.get()
     }
 

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

@@ -304,9 +304,13 @@ impl EmbeddedPisoSolver {
                 inner_stop,
                 anchor_cell,
             );
-            let (s0, i0, c0) = self.poisson_profile.get();
-            self.poisson_profile
-                .set((s0 + solution.setup_ns, i0 + solution.iterate_ns, c0 + 1));
+            let (s0, i0, c0, k0) = self.poisson_profile.get();
+            self.poisson_profile.set((
+                s0 + solution.setup_ns,
+                i0 + solution.iterate_ns,
+                c0 + 1,
+                k0 + solution.iterations as u64,
+            ));
             // Unconverged: fall back to the SOR sweeps for this projection
             // rather than apply a correction that did not reach the stop.
             multigrid_converged = solution.converged;

crates/specialized/rtx-fsi/tests/fsi2_harness/overset.rs

@@ -1164,12 +1164,14 @@ impl OversetFluid {
     /// setup / iterate split.
     pub fn profile_line(&self) -> Option<String> {
         let t = self.solver.timers()?;
-        let (ps, pi, pc) = self.solver.background().poisson_profile();
+        let (ps, pi, pc, pk) = self.solver.background().poisson_profile();
+        let rg = rtx_cfd::mesh::patch_gen::regen_profile();
         let s = |ns: u64| ns as f64 * 1e-9;
         let adv = s(t.advance_ns).max(1e-300);
         let pct = |ns: u64| 100.0 * s(ns) / adv;
-        Some(format!(
-            "  advance split over {} steps ({} rounds), {:.0} s: overlap build {:.0} s ({:.1}%), predictor bg {:.0} s ({:.1}%), predictor patch {:.0} s ({:.1}%), bg Poisson {:.0} s ({:.1}%) [setup {:.0} s, iterate {:.0} s, {} solves], patch BiCGSTAB {:.0} s ({:.1}%), round exchange {:.0} s ({:.1}%), apply {:.0} s ({:.1}%), end exchange {:.0} s ({:.1}%), other {:.0} s",
+        Some(
+            format!(
+                "  advance split over {} steps ({} rounds), {:.0} s: overlap build {:.0} s ({:.1}%), predictor bg {:.0} s ({:.1}%), predictor patch {:.0} s ({:.1}%), bg Poisson {:.0} s ({:.1}%) [setup {:.0} s, iterate {:.0} s, {} solves, {} CG iterations, {:.2} ms per V-cycle], patch BiCGSTAB {:.0} s ({:.1}%), round exchange {:.0} s ({:.1}%), apply {:.0} s ({:.1}%), end exchange {:.0} s ({:.1}%), other {:.0} s",
                 t.steps,
                 t.rounds,
                 adv,
@@ -1184,6 +1186,8 @@ impl OversetFluid {
                 s(ps),
                 s(pi),
                 pc,
+                pk,
+                1e3 * s(pi) / (pk + pc).max(1) as f64,
                 s(t.patch_solve_ns),
                 pct(t.patch_solve_ns),
                 s(t.round_exchange_ns),
@@ -1200,7 +1204,18 @@ impl OversetFluid {
                     + t.round_exchange_ns
                     + t.apply_ns
                     + t.end_exchange_ns),
-        ))
+            ) + &format!(
+                "\n  regeneration split ({} builds): outline {:.0} s, hull + offset {:.0} s, ring projection {:.0} s, Winslow sweeps {:.0} s, respace {:.0} s, warm bookkeeping {:.0} s, mesh finalisation {:.0} s",
+                rg[7],
+                s(rg[0]),
+                s(rg[1]),
+                s(rg[2]),
+                s(rg[3]),
+                s(rg[4]),
+                s(rg[5]),
+                s(rg[6])
+            ),
+        )
     }
 
     pub fn time(&self) -> f64 {