[v1] lib/power: add check for sysfs base frequency
Checks
Commit Message
Some kernels may show in incorrect value for base frequency in
sysfs (e.g. 15 GHz). This throws off the SST-BF algorithm for
high and low priority cores. So if base_frequency is greater
than max turbo frequency, ignore, and handle it as a normal
core.
Known Kernel version with issue: Linux 5.8.7
Signed-off-by: David Hunt <david.hunt@intel.com>
---
lib/librte_power/power_pstate_cpufreq.c | 40 ++++++++++++++++++++++---
1 file changed, 36 insertions(+), 4 deletions(-)
Comments
16/03/2021 10:38, David Hunt:
> Some kernels may show in incorrect value for base frequency in
> sysfs (e.g. 15 GHz). This throws off the SST-BF algorithm for
> high and low priority cores. So if base_frequency is greater
> than max turbo frequency, ignore, and handle it as a normal
> core.
>
> Known Kernel version with issue: Linux 5.8.7
>
> Signed-off-by: David Hunt <david.hunt@intel.com>
Applied, thanks
@@ -154,29 +154,49 @@ out: close(fd);
static int
power_init_for_setting_freq(struct pstate_power_info *pi)
{
- FILE *f_min, *f_max, *f_base;
+ FILE *f_min, *f_max, *f_base = NULL, *f_base_max;
char fullpath_min[PATH_MAX];
char fullpath_max[PATH_MAX];
char fullpath_base[PATH_MAX];
+ char fullpath_base_max[PATH_MAX];
char buf_base[BUFSIZ];
char *s_base;
+ char *s_base_max;
uint32_t base_ratio = 0;
+ uint32_t base_max_ratio = 0;
uint64_t max_non_turbo = 0;
int ret_val = 0;
- snprintf(fullpath_min, sizeof(fullpath_min), POWER_SYSFILE_MIN_FREQ,
+ snprintf(fullpath_base_max,
+ sizeof(fullpath_base_max),
+ POWER_SYSFILE_BASE_MAX_FREQ,
pi->lcore_id);
+ f_base_max = fopen(fullpath_base_max, "r");
+ FOPEN_OR_ERR_RET(f_base_max, -1);
+ if (f_base_max != NULL) {
+ s_base_max = fgets(buf_base, sizeof(buf_base), f_base_max);
+ FOPS_OR_NULL_GOTO(s_base_max, out);
+ buf_base[BUFSIZ-1] = '\0';
+ if (strlen(buf_base))
+ /* Strip off terminating '\n' */
+ strtok(buf_base, "\n");
+
+ base_max_ratio =
+ strtoul(buf_base, NULL, POWER_CONVERT_TO_DECIMAL)
+ / BUS_FREQ;
+ }
+
+ snprintf(fullpath_min, sizeof(fullpath_min), POWER_SYSFILE_MIN_FREQ,
+ pi->lcore_id);
f_min = fopen(fullpath_min, "rw+");
FOPEN_OR_ERR_RET(f_min, -1);
snprintf(fullpath_max, sizeof(fullpath_max), POWER_SYSFILE_MAX_FREQ,
pi->lcore_id);
-
f_max = fopen(fullpath_max, "rw+");
if (f_max == NULL)
fclose(f_min);
-
FOPEN_OR_ERR_RET(f_max, -1);
pi->f_cur_min = f_min;
@@ -186,6 +206,7 @@ power_init_for_setting_freq(struct pstate_power_info *pi)
pi->lcore_id);
f_base = fopen(fullpath_base, "r");
+ FOPEN_OR_ERR_RET(f_base, -1);
if (f_base == NULL) {
/* No sysfs base_frequency, that's OK, continue without */
base_ratio = 0;
@@ -215,6 +236,17 @@ power_init_for_setting_freq(struct pstate_power_info *pi)
pi->non_turbo_max_ratio = max_non_turbo;
+ /*
+ * If base_frequency is reported as greater than the maximum
+ * turbo frequency, that's a known issue with some kernels.
+ * Set base_frequency to max_non_turbo as a workaround.
+ */
+ if (base_ratio > base_max_ratio) {
+ /* base_ratio is greater than max turbo. Kernel bug. */
+ pi->priority_core = 0;
+ goto out;
+ }
+
/*
* If base_frequency is reported as greater than the maximum
* non-turbo frequency, then mark it as a high priority core.