Changeset 78bc398 for doc/theses/mike_brooks_MMath/benchmarks/list/driver.c

Timestamp:

Sep 22, 2025, 2:52:19 PM (6 months ago)

Author:

Michael Brooks <mlbrooks@…>

Branches:

master, stuck-waitfor-destruct

Children:

3d02803

Parents:

bb5b866

Message:

LL perf: small fixes

Fix off-by-one bug in runtime-no-shuf solution. Add safety check that interleaving is off. Re-run.

File:

• doc/theses/mike_brooks_MMath/benchmarks/list/driver.c (modified) (3 diffs)

doc/theses/mike_brooks_MMath/benchmarks/list/driver.c

@@ -60 +60 @@
 #else 
     enum { DefaultNumNodes = 10, DefaultExperimentDurSec = 1, DefaultCheckDonePeriod = 2, DefaultExperimentDurOpCount = 20, DefaultSeed = 5 };
-    const double DefaultInterleaveFrac = 0.5;
+    const double DefaultInterleaveFrac = 0.0;
     static const char * tp_filter
     // = "";
@@ -266 +266 @@
             return 1;
         }
-        // Fill with the ordinals (iota)
-        for (size_t i = 0; i < NumNodes; i++) {
-            insertOrdShuf[i] = i;
-        }
         // Dummy "Seed" of -1 means skip the shuffle: measure overhead of shuffling indirection
-        if (Seed != -1) {
+        if (Seed == -1) {
+            // Fill with the ordinals, shifted left (iota+1)
+            // The specific single-cyle permutation that visits each item in order
+            for (size_t i = 0; i < NumNodes; i++) {
+                insertOrdShuf[i] = (i+1) % NumNodes;
+            }
+        } else {
+            // Fill with the ordinals (iota)
+            for (size_t i = 0; i < NumNodes; i++) {
+                insertOrdShuf[i] = i;
+            }
             // Shuffle per https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#Sattolo's_algorithm
             // Don't want to draw from all permutations, only single-cycle permutations
@@ -371 +377 @@
         // no action required on no-interleave
         if ( InterleaveFrac > 0.0 ) {
+            assert(false && "interleaving was abandoned; always run with InterleaveFrac=0.0");
 
             // assert( ( NumNodes >= 2 * N_INTERLEAVE_ACTION)