diff --git a/examples/006_multisession_drift/pipelines.txt b/examples/006_multisession_drift/pipelines.txt
index 365b1540..e8fb7af5 100644
--- a/examples/006_multisession_drift/pipelines.txt
+++ b/examples/006_multisession_drift/pipelines.txt
@@ -1 +1,2 @@
 m2drift mountainsort2_drift_01.pipeline --num_time_segment_threads=20 --num_basic_sort_threads=2
+pip1 mountainsort2_drift_01.pipeline --num_time_segment_threads=1 --num_basic_sort_threads=1
diff --git a/packages/mountainsort2/algs/basic_sort.js b/packages/mountainsort2/algs/basic_sort.js
index ebc9c6a9..1f2496e8 100644
--- a/packages/mountainsort2/algs/basic_sort.js
+++ b/packages/mountainsort2/algs/basic_sort.js
@@ -200,6 +200,7 @@ exports.run=function(opts,callback) {
 		console.log('****** '+console_prefix+'BASIC SORT STEP '+(ii+1)+' of '+steps.length +' ******');
 		var timer=new Date();
 		step(function(result) {
+			if (!result) result={};
 			console.log ('Elapsed time ['+(result.processor_name||'')+'] (sec): '+get_elapsed_sec(timer));
 			cb();
 		});
diff --git a/packages/mountainsort2/src/mountainsort2_main.cpp b/packages/mountainsort2/src/mountainsort2_main.cpp
index 7b0b93d6..88f32317 100644
--- a/packages/mountainsort2/src/mountainsort2_main.cpp
+++ b/packages/mountainsort2/src/mountainsort2_main.cpp
@@ -189,8 +189,9 @@ int main(int argc, char* argv[])
 
     if (CLP.named_parameters.contains("_request_num_threads")) {
         int num_threads = CLP.named_parameters.value("_request_num_threads", 0).toInt();
-        if (num_threads)
+        if (num_threads) {
             omp_set_num_threads(num_threads);
+        }
     }
 
     if (arg1 == "mountainsort.extract_neighborhood_timeseries") {
diff --git a/packages/mountainsort2/src/p_bandpass_filter.cpp b/packages/mountainsort2/src/p_bandpass_filter.cpp
index f1cc3b1d..fe9fc1ab 100644
--- a/packages/mountainsort2/src/p_bandpass_filter.cpp
+++ b/packages/mountainsort2/src/p_bandpass_filter.cpp
@@ -289,6 +289,7 @@ void define_kernel(int N, double* kernel, double samplefreq, double freq_min, do
 
 Mda32 bandpass_filter_kernel(Mda32& X, double samplerate, double freq_min, double freq_max, double freq_wid)
 {
+    QTime timer; timer.start();
     long M = X.N1();
     long N = X.N2();
     long MN = M * N;
@@ -309,6 +310,10 @@ Mda32 bandpass_filter_kernel(Mda32& X, double samplerate, double freq_min, doubl
     free(kernel0);
     free(Xhat);
 
+    double sec=timer.elapsed()*1.0/1000;
+    double rate=X.totalSize()/sec;
+    printf("bandpass filter rate: %g numbers/sec\n",rate);
+
     return Y;
 }
 }