From mboxrd@z Thu Jan 1 00:00:00 1970 From: yogesh.tillu@linaro.org (Yogesh Tillu) Date: Mon, 3 Nov 2014 20:34:05 +0530 Subject: [RFC PATCH 5/5] Application: to read PMU counter through vdso In-Reply-To: <1415027045-6573-1-git-send-email-yogesh.tillu@linaro.org> References: <1415027045-6573-1-git-send-email-yogesh.tillu@linaro.org> Message-ID: <1415027045-6573-6-git-send-email-yogesh.tillu@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Test application to read PMU cycle counter through vDSO path. Signed-off-by: Yogesh Tillu --- 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 +#include +#include +#include +/* 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