diff --git a/README.md b/README.md
index ce952ef..a1fb8de 100644
--- a/README.md
+++ b/README.md
@@ -68,7 +68,7 @@ All tests support the same set of arguments :
   * `-r,--root <root/all>` Specify which root to use. Only for operations with a root like broadcast or reduce. Default : 0.
 * Performance
   * `-n,--iters <iteration count>` number of iterations. Default : 20.
-  * `-w,--warmup_iters <warmup iteration count>` number of warmup iterations (not timed). Default : 5.
+  * `-w,--warmup_iters <warmup iteration count>` number of warmup iterations (not timed). Default : 1.
   * `-m,--agg_iters <aggregation count>` number of operations to aggregate together in each iteration. Default : 1.
   * `-N,--run_cycles <cycle count>` run & print each cycle. Default : 1; 0=infinite.
   * `-a,--average <0/1/2/3>` Report performance as an average across all ranks (MPI=1 only). <0=Rank0,1=Avg,2=Min,3=Max>. Default : 1.
diff --git a/src/common.cu b/src/common.cu
index 99b1d59..42bc3eb 100644
--- a/src/common.cu
+++ b/src/common.cu
@@ -78,7 +78,7 @@ static size_t maxBytes = 32*1024*1024;
 static size_t stepBytes = 1*1024*1024;
 static size_t stepFactor = 1;
 static int datacheck = 1;
-static int warmup_iters = 5;
+static int warmup_iters = 1;
 static int iters = 20;
 static int agg_iters = 1;
 static int run_cycles = 1;
@@ -607,19 +607,14 @@ testResult_t TimeTest(struct threadArgs* args, ncclDataType_t type, const char*
   // Sync to avoid first-call timeout
   Barrier(args);
 
-  // Warm-up for large size
-  setupArgs(args->maxbytes, type, args);
-  for (int iter = 0; iter < warmup_iters; iter++) {
-    TESTCHECK(startColl(args, type, op, root, 0, iter));
+  // Warm-up for all sizes (using a stepfactor of 2)
+  for (size_t size = args->minbytes; size <= args->maxbytes; size = size * 2) {
+    setupArgs(size, type, args);
+    for (int iter = 0; iter < warmup_iters; iter++) {
+      TESTCHECK(startColl(args, type, op, root, 0, iter));
+    }
+    TESTCHECK(completeColl(args));
   }
-  TESTCHECK(completeColl(args));
-
-  // Warm-up for small size
-  setupArgs(args->minbytes, type, args);
-  for (int iter = 0; iter < warmup_iters; iter++) {
-    TESTCHECK(startColl(args, type, op, root, 0, iter));
-  }
-  TESTCHECK(completeColl(args));
 
   // Benchmark
   long repeat = run_cycles;