In the feedback loops, skip the particles that are not doing feedback.

src/feedback/EAGLE/feedback.h

@@ -44,6 +44,27 @@ __attribute__((always_inline)) INLINE static int feedback_do_feedback(
   return (sp->birth_time != -1.);
 }
 
+/**
+ * @brief Should this particle be doing any feedback-related operation?
+ *
+ * @param sp The #spart.
+ * @param time The current simulation time (Non-cosmological runs).
+ * @param cosmo The cosmological model (cosmological runs).
+ * @param with_cosmology Are we doing a cosmological run?
+ */
+__attribute__((always_inline)) INLINE static int feedback_is_active(
+    const struct spart* sp, const float time, const struct cosmology* cosmo,
+    const int with_cosmology) {
+
+  if (sp->birth_time == -1.) return 0;
+
+  if (with_cosmology) {
+    return ((float)cosmo->a) > sp->birth_scale_factor;
+  } else {
+    return time > sp->birth_time;
+  }
+}
+
 /**
  * @brief Prepares a s-particle for its feedback interactions
  *

src/feedback/none/feedback.h

@@ -45,6 +45,21 @@ __attribute__((always_inline)) INLINE static int feedback_do_feedback(
   return 0;
 }
 
+/**
+ * @brief Should this particle be doing any feedback-related operation?
+ *
+ * @param sp The #spart.
+ * @param time The current simulation time (Non-cosmological runs).
+ * @param cosmo The cosmological model (cosmological runs).
+ * @param with_cosmology Are we doing a cosmological run?
+ */
+__attribute__((always_inline)) INLINE static int feedback_is_active(
+    const struct spart* sp, const float time, const struct cosmology* cosmo,
+    const int with_cosmology) {
+
+  return 0;
+}
+
 /**
  * @brief Prepares a star's feedback field before computing what
  * needs to be distributed.

src/runner.c

@@ -185,7 +185,8 @@ void runner_do_stars_ghost(struct runner *r, struct cell *c, int timer) {
     if ((right = (float *)malloc(sizeof(float) * c->stars.count)) == NULL)
       error("Can't allocate memory for right.");
     for (int k = 0; k < c->stars.count; k++)
-      if (spart_is_active(&sparts[k], e)) {
+      if (spart_is_active(&sparts[k], e) &&
+          feedback_is_active(&sparts[k], e->time, cosmo, with_cosmology)) {
         sid[scount] = k;
         h_0[scount] = sparts[k].h;
         left[scount] = 0.f;
@@ -1608,14 +1609,12 @@ void runner_do_ghost(struct runner *r, struct cell *c, int timer) {
         const float h_init = h_0[i];
         const float h_old = p->h;
         const float h_old_dim = pow_dimension(h_old);
-        // const float h_old_inv_dim = pow_dimension(1.f / h_old);
         const float h_old_dim_minus_one = pow_dimension_minus_one(h_old);
 
         float h_new;
         int has_no_neighbours = 0;
 
-        if (p->density.wcount == 0.f) {
-          // 1e-5 * kernel_root * h_old_inv_dim) { /* No neighbours case */
+        if (p->density.wcount == 0.f) { /* No neighbours case */
 
           /* Flag that there were no neighbours */
           has_no_neighbours = 1;

src/runner_doiact_stars.h

@@ -102,6 +102,7 @@ void DOSELF1_STARS(struct runner *r, struct cell *c, int timer) {
   TIMER_TIC;
 
   const struct engine *e = r->e;
+  const int with_cosmology = e->policy & engine_policy_cosmology;
   const integertime_t ti_current = e->ti_current;
   const struct cosmology *cosmo = e->cosmology;
 
@@ -124,8 +125,13 @@ void DOSELF1_STARS(struct runner *r, struct cell *c, int timer) {
 
     /* Get a hold of the ith spart in ci. */
     struct spart *restrict si = &sparts[sid];
+
+    /* Skip inactive particles */
     if (!spart_is_active(si, e)) continue;
 
+    /* Skip inactive particles */
+    if (!feedback_is_active(si, e->time, cosmo, with_cosmology)) continue;
+
     const float hi = si->h;
     const float hig2 = hi * hi * kernel_gamma2;
     const float six[3] = {(float)(si->x[0] - c->loc[0]),
@@ -191,6 +197,7 @@ void DO_NONSYM_PAIR1_STARS_NAIVE(struct runner *r, struct cell *restrict ci,
 #endif
 
   const struct engine *e = r->e;
+  const int with_cosmology = e->policy & engine_policy_cosmology;
   const integertime_t ti_current = e->ti_current;
   const struct cosmology *cosmo = e->cosmology;
 
@@ -222,8 +229,13 @@ void DO_NONSYM_PAIR1_STARS_NAIVE(struct runner *r, struct cell *restrict ci,
 
     /* Get a hold of the ith spart in ci. */
     struct spart *restrict si = &sparts_i[sid];
+
+    /* Skip inactive particles */
     if (!spart_is_active(si, e)) continue;
 
+    /* Skip inactive particles */
+    if (!feedback_is_active(si, e->time, cosmo, with_cosmology)) continue;
+
     const float hi = si->h;
     const float hig2 = hi * hi * kernel_gamma2;
     const float six[3] = {(float)(si->x[0] - (cj->loc[0] + shift[0])),
@@ -284,6 +296,7 @@ void DO_SYM_PAIR1_STARS(struct runner *r, struct cell *ci, struct cell *cj,
   TIMER_TIC;
 
   const struct engine *e = r->e;
+  const int with_cosmology = e->policy & engine_policy_cosmology;
   const integertime_t ti_current = e->ti_current;
   const struct cosmology *cosmo = e->cosmology;
 
@@ -350,6 +363,9 @@ void DO_SYM_PAIR1_STARS(struct runner *r, struct cell *ci, struct cell *cj,
       /* Skip inactive particles */
       if (!spart_is_active(spi, e)) continue;
 
+      /* Skip inactive particles */
+      if (!feedback_is_active(spi, e->time, cosmo, with_cosmology)) continue;
+
       /* Compute distance from the other cell. */
       const double px[3] = {spi->x[0], spi->x[1], spi->x[2]};
       float dist = px[0] * runner_shift[sid][0] + px[1] * runner_shift[sid][1] +
@@ -475,6 +491,9 @@ void DO_SYM_PAIR1_STARS(struct runner *r, struct cell *ci, struct cell *cj,
       /* Skip inactive particles */
       if (!spart_is_active(spj, e)) continue;
 
+      /* Skip inactive particles */
+      if (!feedback_is_active(spj, e->time, cosmo, with_cosmology)) continue;
+
       /* Compute distance from the other cell. */
       const double px[3] = {spj->x[0], spj->x[1], spj->x[2]};
       float dist = px[0] * runner_shift[sid][0] + px[1] * runner_shift[sid][1] +