Test application to read PMU cycle counter through vDSO path.
Signed-off-by: Yogesh Tillu <[email protected]>
---
vdso_userspace_perf.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 58 insertions(+)
create mode 100644 vdso_userspace_perf.c
diff --git a/vdso_userspace_perf.c b/vdso_userspace_perf.c
new file mode 100644
index 0000000..42d2682
--- /dev/null
+++ b/vdso_userspace_perf.c
@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/time.h>
+/* Simple loop body to keep things interested. Make sure it gets inlined. */
+static inline int
+loop(int* __restrict__ a, int* __restrict__ b, int n)
+{
+ unsigned sum = 0;
+ for (int i = 0; i < n; ++i)
+ if(a[i] > b[i])
+ sum += a[i] + 5;
+ return sum;
+}
+
+int
+main(int ac, char **av)
+{
+ uint32_t time_start = 0;
+ uint32_t time_end = 0;
+ int result=0;
+ int *a = NULL;
+ int *b = NULL;
+ int len = 0;
+ int sum = 0;
+ int i;
+ struct timeval tv;
+
+ if (ac != 2) return -1;
+ len = atoi(av[1]);
+
+ a = malloc(len*sizeof(*a));
+ b = malloc(len*sizeof(*b));
+
+ for (int i = 0; i < len; ++i) {
+ a[i] = i+128;
+ b[i] = i+64;
+ }
+/* Read Counter with Busy loop */
+ perf_open_counter();
+ time_start = perf_read_counter();
+ sum = loop(a, b, len);
+ time_end = perf_read_counter();
+
printf("**********************************************************************\n");
+ printf("Busyloop sum = %d\nTime delta Including Busyloop = %lu
[clockcycle]\n", sum, time_end - time_start);
+
+/* Read Counter with profiling read_counter */
+ time_start = perf_read_counter();
+ perf_read_counter();
+ time_end = perf_read_counter();
+ printf("\nTime delta Without Busyloop = %lu [clockcycle]\n",
time_end - time_start);
+
printf("**********************************************************************\n");
+
+ free(a); free(b);
+ return 0;
+cleanup:
+ return -1;
+}
--
1.7.9.5
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