Messages in this thread Patch in this message | | | From | Wyes Karny <> | Subject | [PATCH v2 2/2] amd_pstate: Add ->fast_switch() callback | Date | Tue, 9 May 2023 18:05:03 +0000 |
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From: "Gautham R. Shenoy" <gautham.shenoy@amd.com>
Schedutil normally calls the adjust_perf callback for drivers with adjust_perf callback available and fast_switch_possible flag set. However, when frequency invariance is disabled and schedutil tries to invoke fast_switch, and that callback is NULL, it schedules a kthread to invoke the target() callback, which could slow down the frequency update.
Prevent the frequency update slow down by implementing the fast_switch callback for amd_pstate.
Signed-off-by: Wyes Karny <wyes.karny@amd.com> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com> --- drivers/cpufreq/amd-pstate.c | 40 ++++++++++++++++++++++++++++-------- 1 file changed, 32 insertions(+), 8 deletions(-)
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 007bfe724a6a..d5758b67b6f3 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -444,9 +444,8 @@ static int amd_pstate_verify(struct cpufreq_policy_data *policy) return 0; } -static int amd_pstate_target(struct cpufreq_policy *policy, - unsigned int target_freq, - unsigned int relation) +static int amd_pstate_update_freq(struct cpufreq_policy *policy, + unsigned int target_freq, bool fast_switch) { struct cpufreq_freqs freqs; struct amd_cpudata *cpudata = policy->driver_data; @@ -465,14 +464,37 @@ static int amd_pstate_target(struct cpufreq_policy *policy, des_perf = DIV_ROUND_CLOSEST(target_freq * cap_perf, cpudata->max_freq); - cpufreq_freq_transition_begin(policy, &freqs); + WARN_ON(fast_switch && !policy->fast_switch_enabled); + /* + * If fast_switch is desired, then there aren't any registered + * transition notifiers. See comment for + * cpufreq_enable_fast_switch(). + */ + if (!fast_switch) + cpufreq_freq_transition_begin(policy, &freqs); + amd_pstate_update(cpudata, min_perf, des_perf, - max_perf, false, policy->governor->flags); - cpufreq_freq_transition_end(policy, &freqs, false); + max_perf, fast_switch, policy->governor->flags); + + if (!fast_switch) + cpufreq_freq_transition_end(policy, &freqs, false); return 0; } +static int amd_pstate_target(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation) +{ + return amd_pstate_update_freq(policy, target_freq, false); +} + +static unsigned int amd_pstate_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq) +{ + return amd_pstate_update_freq(policy, target_freq, true); +} + static void amd_pstate_adjust_perf(unsigned int cpu, unsigned long _min_perf, unsigned long target_perf, @@ -675,9 +697,10 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy) * For shared memory system frequency update takes time that's why * do this in deferred kthread context. */ - if (boot_cpu_has(X86_FEATURE_CPPC)) + if (boot_cpu_has(X86_FEATURE_CPPC)) { current_pstate_driver->adjust_perf = amd_pstate_adjust_perf; - else + policy->fast_switch_possible = true; + } else current_pstate_driver->adjust_perf = NULL; ret = freq_qos_add_request(&policy->constraints, &cpudata->req[0], @@ -1313,6 +1336,7 @@ 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, .init = amd_pstate_cpu_init, .exit = amd_pstate_cpu_exit, .suspend = amd_pstate_cpu_suspend, -- 2.34.1
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