On 2024/1/18 06:51, Ricardo Neri wrote:
[这封邮件来自外部发件人] On Thu, Dec 28, 2023 at 03:57:05PM +0800, Tony W Wang-oc wrote:For Zhaoxin CPUs, the cores' highest frequencies may be different, which means that cores may run at different max frequencies, According to ACPI-spec6 chapter 8.4.7, the per-core highest frequency value can be obtained via cppc. The core with the higher frequency have better performance, which can be called as preferred core. And better performance can be achieved by making the scheduler to run tasks on these preferred cores. The cpufreq driver can use the highest frequency value as the prioriy of core to make the scheduler try to get better performace. More specifically, in the acpi-cpufreq driver use cppc_get_highest_perf() to get highest frequency value of each core, use sched_set_itmt_core_prio() to set highest frequency value as core priority, and use sched_set_itmt_support() provided by ITMT to tell the scheduler to favor on the preferred cores. Signed-off-by: Tony W Wang-oc <TonyWWang-oc@xxxxxxxxxxx> --- drivers/cpufreq/acpi-cpufreq.c | 56 +++++++++++++++++++++++++++++++++- 1 file changed, 55 insertions(+), 1 deletion(-) diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c index 37f1cdf46d29..f4c1ff9e4bb0 100644 --- a/drivers/cpufreq/acpi-cpufreq.c +++ b/drivers/cpufreq/acpi-cpufreq.c @@ -663,8 +663,56 @@ static u64 get_max_boost_ratio(unsigned int cpu) return div_u64(highest_perf << SCHED_CAPACITY_SHIFT, nominal_perf); } + +/* The work item is needed to avoid CPU hotplug locking issues */ +static void sched_itmt_work_fn(struct work_struct *work) +{ + sched_set_itmt_support(); +} + +static DECLARE_WORK(sched_itmt_work, sched_itmt_work_fn); + +static void set_itmt_prio(int cpu) +{ + static bool cppc_highest_perf_diff; + static struct cpumask core_prior_mask; + u64 highest_perf; + static u64 max_highest_perf = 0, min_highest_perf = U64_MAX; + int ret; + + ret = cppc_get_highest_perf(cpu, &highest_perf); + if (ret) + return; + + sched_set_itmt_core_prio(highest_perf, cpu); + cpumask_set_cpu(cpu, &core_prior_mask); + + if (max_highest_perf <= min_highest_perf) { + if (highest_perf > max_highest_perf) + max_highest_perf = highest_perf; + + if (highest_perf < min_highest_perf) + min_highest_perf = highest_perf; + + if (max_highest_perf > min_highest_perf) { + /* + * This code can be run during CPU online under the + * CPU hotplug locks, so sched_set_itmt_support() + * cannot be called from here. Queue up a work item + * to invoke it. + */ + cppc_highest_perf_diff = true; + } + } + + if (cppc_highest_perf_diff && cpumask_equal(&core_prior_mask, cpu_online_mask)) { + pr_debug("queue a work to set itmt enabled\n"); + schedule_work(&sched_itmt_work); + } +}sched_itmt_work and this function is a duplicate of what the intel_pstate driver already does. It might be good if consolidate in a single place if you are going to pursue this approach.
Thanks for your suggestion, will change the patch code in v2. Sorry for late.
