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[1/2] cpufreq: intel_pstate: round up min_perf limits

Message ID 1479774800-126589-1-git-send-email-srinivas.pandruvada@linux.intel.com (mailing list archive)
State Accepted, archived
Delegated to: Rafael Wysocki
Headers show

Commit Message

Srinivas Pandruvada Nov. 22, 2016, 12:33 a.m. UTC 
In some use cases, user wants to enforce a minimum performance limit on
CPUs. But because of simple division the resultant performance is 100 MHz
less than the desired in some cases.

For example when the maximum frequency is 3.50 GHz, setting
scaling_min_frequency to 1.6 GHz always results in 1.5 GHz minimum. With
simple round up, the frequency can be set to 1.6 GHz to minimum in this
case. This round up is already done to max_policy_pct and max_perf, so do
the same for min_policy_pct and min_perf.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 drivers/cpufreq/intel_pstate.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index f07e591..2f27812 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1569,8 +1569,8 @@  static void intel_pstate_update_perf_limits(struct cpufreq_policy *policy,
 	if (policy->max == policy->min) {
 		limits->min_policy_pct = limits->max_policy_pct;
 	} else {
-		limits->min_policy_pct = (policy->min * 100) /
-						policy->cpuinfo.max_freq;
+		limits->min_policy_pct = DIV_ROUND_UP(policy->min * 100,
+						      policy->cpuinfo.max_freq);
 		limits->min_policy_pct = clamp_t(int, limits->min_policy_pct,
 						 0, 100);
 	}
@@ -1591,6 +1591,7 @@  static void intel_pstate_update_perf_limits(struct cpufreq_policy *policy,
 	limits->min_perf = div_fp(limits->min_perf_pct, 100);
 	limits->max_perf = div_fp(limits->max_perf_pct, 100);
 	limits->max_perf = round_up(limits->max_perf, FRAC_BITS);
+	limits->min_perf = round_up(limits->min_perf, FRAC_BITS);
 
 	mutex_unlock(&intel_pstate_limits_lock);