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author | 2017-11-08 20:23:55 +0530 | |
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committer | 2017-11-08 23:59:33 +0100 | |
commit | 07458f6a5171d97511dfbdf6ce549ed2ca0280c7 (patch) | |
tree | 5c55fa92fc2e2971e2654839c3df1535ed96c40b /kernel/sched | |
parent | cpufreq: schedutil: Examine the correct CPU when we update util (diff) | |
download | linux-07458f6a5171d97511dfbdf6ce549ed2ca0280c7.tar.gz linux-07458f6a5171d97511dfbdf6ce549ed2ca0280c7.tar.bz2 linux-07458f6a5171d97511dfbdf6ce549ed2ca0280c7.zip |
cpufreq: schedutil: Reset cached_raw_freq when not in sync with next_freq
'cached_raw_freq' is used to get the next frequency quickly but should
always be in sync with sg_policy->next_freq. There is a case where it is
not and in such cases it should be reset to avoid switching to incorrect
frequencies.
Consider this case for example:
- policy->cur is 1.2 GHz (Max)
- New request comes for 780 MHz and we store that in cached_raw_freq.
- Based on 780 MHz, we calculate the effective frequency as 800 MHz.
- We then see the CPU wasn't idle recently and choose to keep the next
freq as 1.2 GHz.
- Now we have cached_raw_freq is 780 MHz and sg_policy->next_freq is
1.2 GHz.
- Now if the utilization doesn't change in then next request, then the
next target frequency will still be 780 MHz and it will match with
cached_raw_freq. But we will choose 1.2 GHz instead of 800 MHz here.
Fixes: b7eaf1aab9f8 (cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely)
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.12+ <stable@vger.kernel.org> # 4.12+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/cpufreq_schedutil.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index ba0da243fdd8..2f52ec0f1539 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -282,8 +282,12 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, * Do not reduce the frequency if the CPU has not been idle * recently, as the reduction is likely to be premature then. */ - if (busy && next_f < sg_policy->next_freq) + if (busy && next_f < sg_policy->next_freq) { next_f = sg_policy->next_freq; + + /* Reset cached freq as next_freq has changed */ + sg_policy->cached_raw_freq = 0; + } } sugov_update_commit(sg_policy, time, next_f); } |