From 7743e4b9ab225b1fcaf5d41ac46cc6c4d65c7454 Mon Sep 17 00:00:00 2001
From: Jacek Galowicz <jacek.galowicz@rwth-aachen.de>
Date: Sat, 15 Sep 2012 18:20:31 +0200
Subject: [PATCH] Added some comments and fixed a typo.

---
 apps/tests.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/apps/tests.c b/apps/tests.c
index 4164ec5b..37189410 100644
--- a/apps/tests.c
+++ b/apps/tests.c
@@ -188,7 +188,7 @@ static int svm_test(void *arg)
 				GET_B(i,j) = i+j;
 		}
 
-		kputs("Start sequentiell calculation...\n");
+		kputs("Start sequential calculation...\n");
 
 		start = rdtsc();
 		start = rdtsc();
@@ -340,6 +340,7 @@ static int svm_bench(void *arg)
 	svm_barrier(svm_flags);
 	if (!RCCE_IAM) {
 		start = rdtsc();
+		// The pages are created by touching them for the first time.
 		for(i=0; i<size/sizeof(uint32_t); i+=PAGE_SIZE/sizeof(uint32_t))
 			array[i] = 0;
 		end = rdtsc();
@@ -350,6 +351,9 @@ static int svm_bench(void *arg)
 	svm_barrier(svm_flags);
 	if (RCCE_IAM) {
 		start = rdtsc();
+		// Touching these pages from another core means moving them 
+		// to another owner as well as mapping them in the other core's
+		// memory space.
 		for(i=0; i<size/sizeof(uint32_t); i+=PAGE_SIZE/sizeof(uint32_t))
 			array[i] = 1;
 		end = rdtsc();
@@ -360,6 +364,8 @@ static int svm_bench(void *arg)
 	svm_barrier(svm_flags);
 	if (!RCCE_IAM) {
 		start = rdtsc();
+		// Touching the pages from the first core again only involves
+		// moving the pages without the need to map them again.
 		for(i=0; i<size/sizeof(uint32_t); i+=PAGE_SIZE/sizeof(uint32_t))
 			array[i] = 0;
 		end = rdtsc();
@@ -453,6 +459,8 @@ static int measure_ctx_switch(void* arg)
 	for (i=0; i < REPS && stop == 0; i++) {
 		while(id == sid && stop == 0) {
 			t2 = rdtsc();
+			// Calling rdtsc that often it is better
+			// to serialize the calls in the pipeline.
 			cpuid(0,&a,&b,&c,&d);
 		}