Messages in this thread Patch in this message | | | From | Yue Hu <> | Subject | [PATCH] cpufreq: schedutil: Don't use the limits_changed flag any more | Date | Mon, 8 Feb 2021 11:07:23 +0800 |
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From: Yue Hu <huyue2@yulong.com>
The limits_changed flag was introduced by commit 600f5badb78c ("cpufreq: schedutil: Don't skip freq update when limits change") due to race condition where need_freq_update is cleared in get_next_freq() which causes reducing the CPU frequency is ineffective while busy.
But now, the race condition above is gone because get_next_freq() doesn't clear the flag any more after commit 23a881852f3e ("cpufreq: schedutil: Don't skip freq update if need_freq_update is set").
Moreover, need_freq_update currently will be set to true only in sugov_should_update_freq() if CPUFREQ_NEED_UPDATE_LIMITS is not set for the driver. However, limits may have changed at any time. And subsequent frequence update is depending on need_freq_update. So, we may skip this update.
Hence, let's remove it to avoid above issue and make code more simple.
Signed-off-by: Yue Hu <huyue2@yulong.com> --- kernel/sched/cpufreq_schedutil.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 41e498b..7dd85fb 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -40,7 +40,6 @@ struct sugov_policy { struct task_struct *thread; bool work_in_progress; - bool limits_changed; bool need_freq_update; }; @@ -89,11 +88,8 @@ static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time) if (!cpufreq_this_cpu_can_update(sg_policy->policy)) return false; - if (unlikely(sg_policy->limits_changed)) { - sg_policy->limits_changed = false; - sg_policy->need_freq_update = true; + if (unlikely(sg_policy->need_freq_update)) return true; - } delta_ns = time - sg_policy->last_freq_update_time; @@ -323,7 +319,7 @@ static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy) { if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl) - sg_policy->limits_changed = true; + sg_policy->need_freq_update = true; } static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu, @@ -759,7 +755,6 @@ static int sugov_start(struct cpufreq_policy *policy) sg_policy->last_freq_update_time = 0; sg_policy->next_freq = 0; sg_policy->work_in_progress = false; - sg_policy->limits_changed = false; sg_policy->cached_raw_freq = 0; sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS); @@ -813,7 +808,7 @@ static void sugov_limits(struct cpufreq_policy *policy) mutex_unlock(&sg_policy->work_lock); } - sg_policy->limits_changed = true; + sg_policy->need_freq_update = true; } struct cpufreq_governor schedutil_gov = { -- 1.9.1
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