From a25166799925db82fc263f6a74d6f83d439922d5 Mon Sep 17 00:00:00 2001
From: Birte Kristina Friesel <birte.friesel@uos.de>
Date: Mon, 27 Jan 2025 08:33:39 +0100
Subject: add a simple sanity check for (single-threaded) read tests

---
 mbw.c | 41 ++++++++++++++++++++++++++++++++++-------
 1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/mbw.c b/mbw.c
index 25168c3..712bdbf 100644
--- a/mbw.c
+++ b/mbw.c
@@ -3,6 +3,7 @@
  */
 #define _GNU_SOURCE
 
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -83,6 +84,9 @@ unsigned int test_type;
 /* fixed memcpy block size for -t2 */
 unsigned long long block_size=DEFAULT_BLOCK_SIZE;
 
+int sanity_check = 0;
+long arr_a_sum = 0;
+
 #ifdef NUMA
 void* mp_pages[1];
 int mp_status[1];
@@ -342,6 +346,7 @@ void usage()
     printf("Options:\n");
     printf("	-n: number of runs per test (0 to run forever)\n");
     printf("	-a: Don't display average\n");
+    printf("	-C: enable sanity checks\n");
     printf("	-t%d: memcpy test\n", TEST_MEMCPY);
     printf("	-t%d: plain (b[i]=a[i] style) test\n", TEST_PLAIN);
     printf("	-t%d: memcpy test with fixed block size\n", TEST_MCBLOCK);
@@ -370,7 +375,7 @@ void usage()
 
 /* allocate a test array and fill it with data
  * so as to force Linux to _really_ allocate it */
-long *make_array()
+long *make_array(long *sum)
 {
     unsigned long long t;
     unsigned int long_size=sizeof(long);
@@ -391,6 +396,12 @@ long *make_array()
     for(t=0; t<arr_size; t++) {
         a[t]=0xaa;
     }
+    if (sum != NULL) {
+        *sum = 0;
+        for(t=0; t<arr_size; t++) {
+            *sum += 0xaa;
+        }
+    }
     return a;
 }
 
@@ -436,6 +447,9 @@ void *thread_worker(void *arg)
                 tmp += arr_a[t];
             }
             arr_a[plain_stop-1] = tmp;
+            if (sanity_check) {
+                assert(tmp == arr_a_sum);
+            }
         } else if(test_type==TEST_WRITE_PLAIN) {
             long tmp = 1374181804651713298;
             for(t=plain_start; t<plain_stop; t++) {
@@ -551,10 +565,12 @@ double worker()
         long tmp = 0;
         clock_gettime(CLOCK_MONOTONIC, &starttime);
         for(t=0; t<arr_size; t++) {
-            tmp ^= arr_a[t];
+            tmp += arr_a[t];
         }
         clock_gettime(CLOCK_MONOTONIC, &endtime);
-        arr_a[arr_size-1] = tmp;
+        if (sanity_check) {
+            assert(tmp == arr_a_sum);
+        }
     } else if(test_type==TEST_WRITE_PLAIN) {
         long tmp = 0;
         clock_gettime(CLOCK_MONOTONIC, &starttime);
@@ -566,6 +582,7 @@ double worker()
     } else if(test_type==TEST_READ_AVX512) {
         __m512i zmm0 = _mm512_setzero_epi32();
         __m512i zmm1;
+        long tmp = 0;
         uint8_t *src = (uint8_t*)arr_a;
         const uint8_t *end = src + arr_size * sizeof(long);
         clock_gettime(CLOCK_MONOTONIC, &starttime);
@@ -575,7 +592,14 @@ double worker()
             src += 64;
         }
         clock_gettime(CLOCK_MONOTONIC, &endtime);
-        arr_a[arr_size-1] = (long)_mm512_reduce_add_epi64(zmm0);
+        tmp = (long)_mm512_reduce_add_epi64(zmm0);
+        if (sanity_check) {
+            if (tmp != arr_a_sum) {
+                printf("expected:       arr_a_sum == %12ld (%016lx)\n", arr_a_sum, arr_a_sum);
+                printf("output: arr_a[arr_size-1] == %12ld (%016lx)\n", tmp, tmp);
+            }
+            assert(tmp == arr_a_sum);
+        }
     } else if(test_type==TEST_WRITE_AVX512) {
         const uint8_t *src = (uint8_t*)arr_b;
         uint8_t *dst = (uint8_t*)arr_b;
@@ -650,7 +674,7 @@ int main(int argc, char **argv)
     tests[6]=0;
     tests[7]=0;
 
-    while((o=getopt(argc, argv, "ha:b:c:qn:N:t:B:")) != EOF) {
+    while((o=getopt(argc, argv, "ha:b:c:qn:N:t:B:C")) != EOF) {
         switch(o) {
             case 'h':
                 usage();
@@ -690,6 +714,9 @@ int main(int argc, char **argv)
                     exit(1);
                 }
                 break;
+            case 'C':
+                sanity_check = 1;
+                break;
             case 'q': /* quiet */
                 quiet=1;
                 break;
@@ -770,7 +797,7 @@ int main(int argc, char **argv)
         if (!quiet) {
             printf("Allocating %lld elements = %lld MiB of input memory.\n", arr_size, arr_size*long_size / 1024 / 1024);
         }
-        arr_a=make_array();
+        arr_a=make_array(&arr_a_sum);
     }
 
 #ifdef NUMA
@@ -783,7 +810,7 @@ int main(int argc, char **argv)
         if (!quiet) {
             printf("Allocating %lld elements = %lld MiB of output memory.\n", arr_size, arr_size*long_size / 1024 / 1024);
         }
-        arr_b=make_array();
+        arr_b=make_array(NULL);
     }
 
 #ifdef NUMA
-- 
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