[dpdk-dev] [PATCH v4 2/2] test/power: add delay before checking cpuinfo cur freq

[Richael Zhuang]

For some platforms the newly-set frequency may not be effective
immediately. If we didn't get the right value from cpuinfo_cur_freq
immediately, add 10ms delay each time before rechecking until
timeout.

>From our test, for some arm platforms, it requires up to 700ms when
going from a minimum to a maximum frequency. And it's not the
driver/software issue.

Fixes: ed7c51a6a680 ("app/test: vm power management")
Cc: alan.ca...@intel.com
Cc: sta...@dpdk.org

Signed-off-by: Richael Zhuang <richael.zhu...@arm.com>
---
 app/test/test_power_cpufreq.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/app/test/test_power_cpufreq.c b/app/test/test_power_cpufreq.c
index 1f4d8bb05..25249ecf5 100644
--- a/app/test/test_power_cpufreq.c
+++ b/app/test/test_power_cpufreq.c
@@ -8,6 +8,7 @@
 #include <limits.h>
 #include <string.h>
 #include <inttypes.h>
+#include <rte_cycles.h>
 
 #include "test.h"
 
@@ -48,11 +49,13 @@ static int
 check_cur_freq(unsigned lcore_id, uint32_t idx)
 {
 #define TEST_POWER_CONVERT_TO_DECIMAL 10
+#define MAX_LOOP 100
        FILE *f;
        char fullpath[PATH_MAX];
        char buf[BUFSIZ];
        uint32_t cur_freq;
        int ret = -1;
+       int i;
 
        if (snprintf(fullpath, sizeof(fullpath),
                TEST_POWER_SYSFILE_CUR_FREQ, lcore_id) < 0) {
@@ -62,8 +65,24 @@ check_cur_freq(unsigned lcore_id, uint32_t idx)
        if (f == NULL) {
                return 0;
        }
-       if (fgets(buf, sizeof(buf), f) == NULL) {
-               goto fail_get_cur_freq;
+       for (i = 0; i < MAX_LOOP; i++) {
+               fflush(f);
+               if (fgets(buf, sizeof(buf), f) == NULL)
+                       goto fail_all;
+
+               cur_freq = strtoul(buf, NULL, TEST_POWER_CONVERT_TO_DECIMAL);
+               ret = (freqs[idx] == cur_freq ? 0 : -1);
+
+               if (ret == 0)
+                       break;
+
+               if (fseek(f, 0, SEEK_SET) < 0) {
+                       printf("Fail to set file position indicator to 0\n");
+                       goto fail_all;
+               }
+
+               /* wait for the value to be updated */
+               rte_delay_ms(10);
        }
        cur_freq = strtoul(buf, NULL, TEST_POWER_CONVERT_TO_DECIMAL);
 
@@ -78,7 +97,7 @@ check_cur_freq(unsigned lcore_id, uint32_t idx)
 
        ret = (freqs[idx] == freq_conv ? 0 : -1);
 
-fail_get_cur_freq:
+fail_all:
        fclose(f);
 
        return ret;
-- 
2.20.1