| Message ID | 20250115100123.241110-2-zhenglifeng1@huawei.com |
|---|---|
| State | New |
| Headers | show |
| Series | cpufreq: Introduce a more generic way to boost when cpu is going online | expand |
On Wed, Jan 15, 2025 at 12:18 PM Viresh Kumar <viresh.kumar@linaro.org> wrote: > > On 15-01-25, 18:01, Lifeng Zheng wrote: > > It turns out that cpuX will stay on the base frequency after performing > > these operations: > > > > 1. boost all cpus: echo 1 > /sys/devices/system/cpu/cpufreq/boost > > > > 2. offline the cpu: echo 0 > /sys/devices/system/cpu/cpuX/online > > > > 3. deboost all cpus: echo 0 > /sys/devices/system/cpu/cpufreq/boost > > > > 4. online the cpu: echo 1 > /sys/devices/system/cpu/cpuX/online > > > > 5. boost all cpus again: echo 1 > /sys/devices/system/cpu/cpufreq/boost > > > > This is because max_freq_req of the policy is not updated during the > > online process, and the value of max_freq_req before the last offline is > > retained. When the CPU is boosted again, freq_qos_update_request() will > > do nothing because the old value is the same as the new one. This causes > > the CPU stay on the base frequency. Update max_freq_req (and > > min_freq_req of course) in cpufreq_online() will solve this problem. > > > > Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com> > > --- > > drivers/cpufreq/cpufreq.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > index 1a4cae54a01b..03ae879d50b9 100644 > > --- a/drivers/cpufreq/cpufreq.c > > +++ b/drivers/cpufreq/cpufreq.c > > @@ -1475,6 +1475,13 @@ static int cpufreq_online(unsigned int cpu) > > > > blocking_notifier_call_chain(&cpufreq_policy_notifier_list, > > CPUFREQ_CREATE_POLICY, policy); > > + } else { > > + ret = freq_qos_update_request(policy->min_freq_req, policy->min); > > This may not be required, as min-freq-req is never updated. It gets updated via scaling_min_freq AFAICS. Doesn't this matter? > > + if (ret < 0) > > + goto out_destroy_policy; > > + ret = freq_qos_update_request(policy->max_freq_req, policy->max); > > + if (ret < 0) > > + goto out_destroy_policy; > > } > > > > if (cpufreq_driver->get && has_target()) { > > --
On 2025/1/15 20:50, Rafael J. Wysocki wrote: > On Wed, Jan 15, 2025 at 12:18 PM Viresh Kumar <viresh.kumar@linaro.org> wrote: >> >> On 15-01-25, 18:01, Lifeng Zheng wrote: >>> It turns out that cpuX will stay on the base frequency after performing >>> these operations: >>> >>> 1. boost all cpus: echo 1 > /sys/devices/system/cpu/cpufreq/boost >>> >>> 2. offline the cpu: echo 0 > /sys/devices/system/cpu/cpuX/online >>> >>> 3. deboost all cpus: echo 0 > /sys/devices/system/cpu/cpufreq/boost >>> >>> 4. online the cpu: echo 1 > /sys/devices/system/cpu/cpuX/online >>> >>> 5. boost all cpus again: echo 1 > /sys/devices/system/cpu/cpufreq/boost >>> >>> This is because max_freq_req of the policy is not updated during the >>> online process, and the value of max_freq_req before the last offline is >>> retained. When the CPU is boosted again, freq_qos_update_request() will >>> do nothing because the old value is the same as the new one. This causes >>> the CPU stay on the base frequency. Update max_freq_req (and >>> min_freq_req of course) in cpufreq_online() will solve this problem. >>> >>> Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com> >>> --- >>> drivers/cpufreq/cpufreq.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >>> index 1a4cae54a01b..03ae879d50b9 100644 >>> --- a/drivers/cpufreq/cpufreq.c >>> +++ b/drivers/cpufreq/cpufreq.c >>> @@ -1475,6 +1475,13 @@ static int cpufreq_online(unsigned int cpu) >>> >>> blocking_notifier_call_chain(&cpufreq_policy_notifier_list, >>> CPUFREQ_CREATE_POLICY, policy); >>> + } else { >>> + ret = freq_qos_update_request(policy->min_freq_req, policy->min); >> >> This may not be required, as min-freq-req is never updated. > > It gets updated via scaling_min_freq AFAICS. Doesn't this matter? If fact, scaling_min_freq cannot be operated when a cpu is offline. So this update may indeed be unnecessary. > >>> + if (ret < 0) >>> + goto out_destroy_policy; >>> + ret = freq_qos_update_request(policy->max_freq_req, policy->max); >>> + if (ret < 0) >>> + goto out_destroy_policy; >>> } >>> >>> if (cpufreq_driver->get && has_target()) { >>> --
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 1a4cae54a01b..03ae879d50b9 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1475,6 +1475,13 @@ static int cpufreq_online(unsigned int cpu) blocking_notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_CREATE_POLICY, policy); + } else { + ret = freq_qos_update_request(policy->min_freq_req, policy->min); + if (ret < 0) + goto out_destroy_policy; + ret = freq_qos_update_request(policy->max_freq_req, policy->max); + if (ret < 0) + goto out_destroy_policy; } if (cpufreq_driver->get && has_target()) {
It turns out that cpuX will stay on the base frequency after performing these operations: 1. boost all cpus: echo 1 > /sys/devices/system/cpu/cpufreq/boost 2. offline the cpu: echo 0 > /sys/devices/system/cpu/cpuX/online 3. deboost all cpus: echo 0 > /sys/devices/system/cpu/cpufreq/boost 4. online the cpu: echo 1 > /sys/devices/system/cpu/cpuX/online 5. boost all cpus again: echo 1 > /sys/devices/system/cpu/cpufreq/boost This is because max_freq_req of the policy is not updated during the online process, and the value of max_freq_req before the last offline is retained. When the CPU is boosted again, freq_qos_update_request() will do nothing because the old value is the same as the new one. This causes the CPU stay on the base frequency. Update max_freq_req (and min_freq_req of course) in cpufreq_online() will solve this problem. Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com> --- drivers/cpufreq/cpufreq.c | 7 +++++++ 1 file changed, 7 insertions(+)