Re: [PATCH v3 07/21] cpufreq: amd: add fast switch function for amd-pstate
From: "Limonciello, Mario" <mario.limonciello@amd.com>
Date: 2021-10-29 14:16:53
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On 10/29/2021 08:02, Huang Rui wrote:
Introduce the fast switch function for amd-pstate on the AMD processors which support the full MSR register control. It's able to decrease the lattency on interrupt context.
s/lattency/latency/
quoted hunk ↗ jump to hunk
Signed-off-by: Huang Rui <ray.huang@amd.com> --- drivers/cpufreq/amd-pstate.c | 38 ++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+)diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index a400861c7fdc..55ff03f85608 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c@@ -191,6 +191,41 @@ static int amd_pstate_target(struct cpufreq_policy *policy, return 0; } +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 int amd_get_min_freq(struct amd_cpudata *cpudata) { struct cppc_perf_caps cppc_perf;@@ -311,6 +346,8 @@ 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) {@@ -360,6 +397,7 @@ static struct cpufreq_driver amd_pstate_driver = { .flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_UPDATE_LIMITS, .verify = amd_pstate_verify, .target = amd_pstate_target, + .adjust_perf = amd_pstate_adjust_perf, .init = amd_pstate_cpu_init, .exit = amd_pstate_cpu_exit, .name = "amd-pstate",