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authorPrarit Bhargava <prarit@redhat.com>2015-11-20 18:47:56 -0500
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-11-23 23:14:10 +0100
commit8478f53946f01b8365a206ac58a2640e3e408fb2 (patch)
tree48bc2f7b6e6cda141b7685d89f3750c669c62ae0 /drivers/cpufreq
parentf344dae0fe9f88d3c7ec45f2d7bba84d6ce1ac00 (diff)
cpufreq: intel_pstate: Fix limits->max_policy_pct rounding error
I have a Intel (6,63) processor with a "marketing" frequency (from /proc/cpuinfo) of 2100MHz, and a max turbo frequency of 2600MHz. I can execute cpupower frequency-set -g powersave --min 1200MHz --max 2100MHz and the max_freq_pct is set to 80. When adding load to the system I noticed that the cpu frequency only reached 2000MHZ and not 2100MHz as expected. This is because limits->max_policy_pct is calculated as 2100 * 100 /2600 = 80.7 and is rounded down to 80 when it should be rounded up to 81. This patch adds a DIV_ROUND_UP() which will return the correct value. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/intel_pstate.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 001a532e342e..eb75053f1371 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1108,7 +1108,8 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
limits = &powersave_limits;
limits->min_policy_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
limits->min_policy_pct = clamp_t(int, limits->min_policy_pct, 0 , 100);
- limits->max_policy_pct = (policy->max * 100) / policy->cpuinfo.max_freq;
+ limits->max_policy_pct = DIV_ROUND_UP(policy->max * 100,
+ policy->cpuinfo.max_freq);
limits->max_policy_pct = clamp_t(int, limits->max_policy_pct, 0 , 100);
/* Normalize user input to [min_policy_pct, max_policy_pct] */