@@ -95,15 +95,8 @@ static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
if (sg_policy->work_in_progress)
return false;
- if (unlikely(sg_policy->need_freq_update)) {
- sg_policy->need_freq_update = false;
- /*
- * This happens when limits change, so forget the previous
- * next_freq value and force an update.
- */
- sg_policy->next_freq = UINT_MAX;
+ if (unlikely(sg_policy->need_freq_update))
return true;
- }
delta_ns = time - sg_policy->last_freq_update_time;
@@ -165,8 +158,10 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,
freq = (freq + (freq >> 2)) * util / max;
- if (freq == sg_policy->cached_raw_freq && sg_policy->next_freq != UINT_MAX)
+ if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
return sg_policy->next_freq;
+
+ sg_policy->need_freq_update = false;
sg_policy->cached_raw_freq = freq;
return cpufreq_driver_resolve_freq(policy, freq);
}
@@ -305,8 +300,7 @@ 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 &&
- sg_policy->next_freq != UINT_MAX) {
+ if (busy && next_f < sg_policy->next_freq) {
next_f = sg_policy->next_freq;
/* Reset cached freq as next_freq has changed */
@@ -671,7 +665,7 @@ static int sugov_start(struct cpufreq_policy *policy)
sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
sg_policy->last_freq_update_time = 0;
- sg_policy->next_freq = UINT_MAX;
+ sg_policy->next_freq = 0;
sg_policy->work_in_progress = false;
sg_policy->need_freq_update = false;
sg_policy->cached_raw_freq = 0;
The schedutil driver sets sg_policy->next_freq to UINT_MAX on certain occasions to discard the cached value of next freq: - In sugov_start(), when the schedutil governor is started for a group of CPUs. - And whenever we need to force a freq update before rate-limit duration, which happens when: - there is an update in cpufreq policy limits. - Or when the utilization of DL scheduling class increases. In return, get_next_freq() doesn't return a cached next_freq value but recalculates the next frequency instead. But having special meaning for a particular value of frequency makes the code less readable and error prone. We recently fixed a bug where the UINT_MAX value was considered as valid frequency in sugov_update_single(). All we need is a flag which can be used to discard the value of sg_policy->next_freq and we already have need_freq_update for that. Lets reuse it instead of setting next_freq to UINT_MAX. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- V2: - Rebased over the fix sent by Rafael lkml.kernel.org/r/2276196.ev9rMjHTR0@aspire.rjw.lan - Remove the additional check from sugov_update_single() as well. - This is for 4.18 now instead of stable kernels. kernel/sched/cpufreq_schedutil.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) -- 2.15.0.194.g9af6a3dea062