Messages in this thread Patch in this message | | | From | Huang Rui <> | Subject | [PATCH 05/19] cpufreq: amd: add fast switch function for amd-pstate module | Date | Wed, 8 Sep 2021 22:59:47 +0800 |
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Introduce the fast switch function for amd-pstate module on the AMD processors which support the full MSR register control. It's able to decrease the lattency on interrupt context.
Signed-off-by: Huang Rui <ray.huang@amd.com> --- drivers/cpufreq/amd-pstate.c | 64 ++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+)
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 4c9c9bf1d72b..32b4f6d79783 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -212,6 +212,66 @@ static int amd_pstate_target(struct cpufreq_policy *policy, return ret; } +static void amd_pstate_adjust_perf(unsigned int cpu, + unsigned long min_perf, + unsigned long target_perf, + unsigned long capacity) +{ + unsigned long amd_max_perf, amd_min_perf, amd_des_perf, + amd_cap_perf, lowest_nonlinear_perf; + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); + struct amd_cpudata *cpudata = policy->driver_data; + + amd_cap_perf = READ_ONCE(cpudata->highest_perf); + lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf); + + if (target_perf < capacity) + amd_des_perf = DIV_ROUND_UP(amd_cap_perf * target_perf, + capacity); + + amd_min_perf = READ_ONCE(cpudata->highest_perf); + if (min_perf < capacity) + amd_min_perf = DIV_ROUND_UP(amd_cap_perf * min_perf, capacity); + + if (amd_min_perf < lowest_nonlinear_perf) + amd_min_perf = lowest_nonlinear_perf; + + amd_max_perf = amd_cap_perf; + if (amd_max_perf < amd_min_perf) + amd_max_perf = amd_min_perf; + + amd_des_perf = clamp_t(unsigned long, amd_des_perf, + amd_min_perf, amd_max_perf); + + amd_pstate_update(cpudata, amd_min_perf, amd_des_perf, + amd_max_perf, true); +} + +static unsigned int amd_pstate_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq) +{ + u64 ratio; + struct amd_cpudata *cpudata = policy->driver_data; + unsigned long amd_max_perf, amd_min_perf, amd_des_perf, nominal_perf; + + if (!cpudata->max_freq) + return -ENODEV; + + amd_max_perf = READ_ONCE(cpudata->highest_perf); + amd_min_perf = READ_ONCE(cpudata->lowest_nonlinear_perf); + + amd_des_perf = DIV_ROUND_UP(target_freq * amd_max_perf, + cpudata->max_freq); + + amd_pstate_update(cpudata, amd_min_perf, amd_des_perf, + amd_max_perf, true); + + nominal_perf = READ_ONCE(cpudata->nominal_perf); + ratio = div_u64(amd_des_perf << SCHED_CAPACITY_SHIFT, nominal_perf); + + return cpudata->nominal_freq * ratio >> SCHED_CAPACITY_SHIFT; +} + static int amd_get_min_freq(struct amd_cpudata *cpudata) { struct cppc_perf_caps cppc_perf; @@ -356,6 +416,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy) /* It will be updated by governor */ policy->cur = policy->cpuinfo.min_freq; + policy->fast_switch_possible = true; + ret = freq_qos_add_request(&policy->constraints, &cpudata->req[0], FREQ_QOS_MIN, policy->cpuinfo.min_freq); if (ret < 0) { @@ -408,6 +470,8 @@ static struct cpufreq_driver amd_pstate_driver = { .flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_UPDATE_LIMITS, .verify = amd_pstate_verify, .target = amd_pstate_target, + .fast_switch = amd_pstate_fast_switch, + .adjust_perf = amd_pstate_adjust_perf, .init = amd_pstate_cpu_init, .exit = amd_pstate_cpu_exit, .name = "amd-pstate", -- 2.25.1
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