mg2d: log the convergence factors after relax/correct

1 files changed, 29 insertions, 5 deletions

diff --git a/mg2d.c b/mg2d.c
index 2fef7f9..81b1b46 100644
--- a/mg2d.c
+++ b/mg2d.c
@@ -73,6 +73,18 @@ static void log_callback(MG2DLogger *log, int level, const char *fmt, va_list vl
     ctx->log_callback(ctx, level, fmt, vl);
 }
 
+static void log_relax_step(MG2DContext *ctx, MG2DLevel *level, const char *step_desc,
+                           double res_old, double res_new)
+{
+    char prefix[32] = { 0 };
+
+    for (int i = 0; i < MIN(sizeof(prefix) - 1, level->depth); i++)
+        prefix[i] = ' ';
+
+    mg2di_log(&ctx->priv->logger, MG2D_LOG_DEBUG, "%s[%d]%s %g->%g (%g)\n",
+              prefix, level->depth, step_desc, res_old, res_new, res_old / res_new);
+}
+
 static void mg_restrict_inject(EllRelaxContext *coarse, double *dst, ptrdiff_t dst_stride,
                                EllRelaxContext *fine, const double *src, ptrdiff_t src_stride)
 {
@@ -241,18 +253,26 @@ static void prolong_solution(MG2DContext *ctx, MG2DLevel *dst, MG2DLevel *src)
     }
 }
 
-static int mg_relax_step(MG2DLevel *level)
+static int mg_relax_step(MG2DContext *ctx, MG2DLevel *level, const char *step_desc)
 {
+    double res_old;
     int64_t start;
     int ret;
 
+    res_old = level->solver->residual_max;
+
     start = gettime();
 
     ret = mg2di_ell_relax_step(level->solver);
 
     level->time_relax += gettime() - start;
 
-    return ret;
+    if (ret < 0)
+        return ret;
+
+    log_relax_step(ctx, level, step_desc, res_old, level->solver->residual_max);
+
+    return 0;
 }
 
 static int mg_solve_subgrid(MG2DContext *ctx, MG2DLevel *level)
@@ -278,7 +298,7 @@ static int mg_solve_subgrid(MG2DContext *ctx, MG2DLevel *level)
     if (!level->child) {
 
         for (int j = 0; j < 16; j++) {
-            ret = mg_relax_step(level);
+            ret = mg_relax_step(ctx, level, "coarse-step");
             if (ret < 0)
                 return ret;
         }
@@ -288,11 +308,12 @@ static int mg_solve_subgrid(MG2DContext *ctx, MG2DLevel *level)
     }
 
     for (int i = 0; i < ctx->nb_cycles; i++) {
+        double res_prev;
         int64_t start;
 
         /* pre-restrict relaxation */
         for (int j = 0; j < ctx->nb_relax_pre; j++) {
-            ret = mg_relax_step(level);
+            ret = mg_relax_step(ctx, level, "pre-relax");
             if (ret < 0)
                 return ret;
         }
@@ -320,15 +341,18 @@ static int mg_solve_subgrid(MG2DContext *ctx, MG2DLevel *level)
         level->time_correct += gettime() - start;
 
         /* re-init the current-level solver (re-calc the residual) */
+        res_prev = level->solver->residual_max;
         start = gettime();
         ret = mg2di_ell_relax_init(level->solver);
         if (ret < 0)
             return ret;
         level->time_reinit += gettime() - start;
 
+        log_relax_step(ctx, level, "correct", res_prev, level->solver->residual_max);
+
         /* post-correct relaxation */
         for (int j = 0; j < ctx->nb_relax_post; j++) {
-            ret = mg_relax_step(level);
+            ret = mg_relax_step(ctx, level, "post-relax");
             if (ret < 0)
                 return ret;
         }