Messages in this thread Patch in this message | | | Date | Fri, 3 Nov 2023 18:56:13 +0800 | Subject | Re: [PATCH v2 3/5] cpufreq: intel_pstate: Add ->offline and ->online callbacks | From | Jinjie Ruan <> |
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On 2020/8/25 1:43, Rafael J. Wysocki wrote: > From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> > > Add ->offline and ->online driver callbacks to prepare for taking a > CPU offline and to restore its working configuration when it goes > back online, respectively, to avoid invoking the ->init callback on > every CPU online which is quite a bit of unnecessary overhead. > > Define ->offline and ->online so that they can be used in the > passive mode as well as in the active mode and because ->offline > will do the majority of ->stop_cpu work, the passive mode does > not need that callback any more, so drop it. > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > > -> v2: Typo fixes and changelog edits (Doug). > > --- > drivers/cpufreq/intel_pstate.c | 38 ++++++++++++++++++++++++++++------ > 1 file changed, 32 insertions(+), 6 deletions(-) > > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > index 3d18934fa975..98836ac299db 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -2297,28 +2297,51 @@ static int intel_pstate_verify_policy(struct cpufreq_policy_data *policy) > return 0; > } > > -static void intel_cpufreq_stop_cpu(struct cpufreq_policy *policy) > +static int intel_pstate_cpu_offline(struct cpufreq_policy *policy) > { > + pr_debug("CPU %d going offline\n", policy->cpu); > + > + intel_pstate_exit_perf_limits(policy); > + > + /* > + * If the CPU is an SMT thread and it goes offline with the performance > + * settings different from the minimum, it will prevent its sibling > + * from getting to lower performance levels, so force the minimum > + * performance on CPU offline to prevent that from happening. > + */ > if (hwp_active) > intel_pstate_hwp_force_min_perf(policy->cpu); > else > intel_pstate_set_min_pstate(all_cpu_data[policy->cpu]); > + > + return 0; > +} > + > +static int intel_pstate_cpu_online(struct cpufreq_policy *policy) > +{ > + pr_debug("CPU %d going online\n", policy->cpu); > + > + intel_pstate_init_acpi_perf_limits(policy); > + > + if (hwp_active) > + wrmsrl_on_cpu(policy->cpu, MSR_HWP_REQUEST, > + all_cpu_data[policy->cpu]->hwp_req_cached); > + > + return 0; > }
On Ice Lake server, there seems a bug when CONFIG_X86_INTEL_PSTATE=y and not configure intel_pstate=xxx in command line.
Although the Performance tuner is used, the CPU have the lowest frequency in scaling_cur_freq after the CPU goes offline and then goes online, running the same infinite loop load.
How to produce:
echo performance > /sys/devices/system/cpu/cpu12/cpufreq/scaling_governor
cat while_true.c #include <stdio.h> void main(void) { while(1); }
[root@localhost freq_test]# cat test.sh #!/bin/bash
cat /sys/devices/system/cpu/cpu${1}/cpufreq/scaling_cur_freq cat /sys/devices/system/cpu/cpu${1}/cpufreq/scaling_governor taskset -c ${1} ./while_true & sleep 1s
cat /sys/devices/system/cpu/cpu${1}/cpufreq/scaling_cur_freq
echo 0 > /sys/devices/system/cpu/cpu${1}/online
sleep 1s cat /sys/devices/system/cpu/cpu${1}/cpufreq/scaling_cur_freq
sleep 1s
echo 1 > /sys/devices/system/cpu/cpu${1}/online cat /sys/devices/system/cpu/cpu${1}/cpufreq/scaling_cur_freq
taskset -c ${1} ./while_true &
sleep 1s cat /sys/devices/system/cpu/cpu${1}/cpufreq/scaling_cur_freq
sleep 1s cat /sys/devices/system/cpu/cpu${1}/cpufreq/scaling_cur_freq
sleep 1s cat /sys/devices/system/cpu/cpu${1}/cpufreq/scaling_cur_freq
[root@localhost freq_test]# sh test.sh 40 2300000 performance 2299977 cat: /sys/devices/system/cpu/cpu40/cpufreq/scaling_cur_freq: Device or resource busy 2300000 2300022 2300000 2299953 [root@localhost freq_test]# sh test.sh 50 2300000 performance 2300000 cat: /sys/devices/system/cpu/cpu50/cpufreq/scaling_cur_freq: Device or resource busy 2300000 2299977 2300022 2299977 [root@localhost freq_test]# sh test.sh 20 2300000 performance 2299977 cat: /sys/devices/system/cpu/cpu20/cpufreq/scaling_cur_freq: Device or resource busy 800000 800000 800000 799992 [root@localhost freq_test]# sh test.sh 21 2300000 performance 2300000 cat: /sys/devices/system/cpu/cpu21/cpufreq/scaling_cur_freq: Device or resource busy 800000 800000 800000 800000
[root@localhost freq_test]# cat /sys/devices/system/cpu/cpu21/cpufreq/scaling_max_freq 2300000 [root@localhost freq_test]# cat /sys/devices/system/cpu/cpu21/cpufreq/scaling_min_freq 800000
> > static void intel_pstate_stop_cpu(struct cpufreq_policy *policy) > { > - pr_debug("CPU %d exiting\n", policy->cpu); > + pr_debug("CPU %d stopping\n", policy->cpu); > > intel_pstate_clear_update_util_hook(policy->cpu); > if (hwp_active) > intel_pstate_hwp_save_state(policy); > - > - intel_cpufreq_stop_cpu(policy); > } > > static int intel_pstate_cpu_exit(struct cpufreq_policy *policy) > { > - intel_pstate_exit_perf_limits(policy); > + pr_debug("CPU %d exiting\n", policy->cpu); > > policy->fast_switch_possible = false; > > @@ -2398,6 +2421,8 @@ static struct cpufreq_driver intel_pstate = { > .init = intel_pstate_cpu_init, > .exit = intel_pstate_cpu_exit, > .stop_cpu = intel_pstate_stop_cpu, > + .offline = intel_pstate_cpu_offline, > + .online = intel_pstate_cpu_online, > .update_limits = intel_pstate_update_limits, > .name = "intel_pstate", > }; > @@ -2652,7 +2677,8 @@ static struct cpufreq_driver intel_cpufreq = { > .fast_switch = intel_cpufreq_fast_switch, > .init = intel_cpufreq_cpu_init, > .exit = intel_cpufreq_cpu_exit, > - .stop_cpu = intel_cpufreq_stop_cpu, > + .offline = intel_pstate_cpu_offline, > + .online = intel_pstate_cpu_online, > .update_limits = intel_pstate_update_limits, > .name = "intel_cpufreq", > };
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