From e303a832d93e66e691ae08fd39d9969355da4955 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 8 Nov 2017 19:47:36 +0530 Subject: BACKPORT: schedutil: Reset cached freq if it is 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 are cases 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 decide not to update the frequency as sugov_up_down_rate_limit() return true. - Here cached_raw_freq is 780 MHz and sg_policy->next_freq is 1.2 GHz. - Now if the utilization doesn't change in next request, then the next target frequency will still be 780 MHz and it will match with cached_raw_freq and so we will directly return 1.2 GHz instead of 800 MHz. BACKPORT of upstream commit 07458f6a5171 ("cpufreq: schedutil: Reset cached_raw_freq when not in sync with next_freq"). This also updates sugov_update_commit() for handling up/down tunables, which aren't present in mainline. Change-Id: I70bca2c5dfdb545a0471d1c9e4c5addb30ab5494 Signed-off-by: Viresh Kumar --- kernel/sched/cpufreq_schedutil.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index d3765f0cb699..6c84b4d28914 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -130,8 +130,11 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time, { struct cpufreq_policy *policy = sg_policy->policy; - if (sugov_up_down_rate_limit(sg_policy, time, next_freq)) + if (sugov_up_down_rate_limit(sg_policy, time, next_freq)) { + /* Reset cached freq as next_freq isn't changed */ + sg_policy->cached_raw_freq = 0; return; + } if (sg_policy->next_freq == next_freq) return; @@ -317,8 +320,12 @@ 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); } -- cgit v1.2.3