我有这个 CPU（输出cat /proc/cpuinfo）
processor : 15
vendor_id : GenuineIntel
cpu family : 6
model : 63
model name : Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz
stepping : 2
microcode : 0x49
cpu MHz : 2956.072
cache size : 20480 KB
physical id : 1
siblings : 8
core id : 7
cpu cores : 8
apicid : 30
initial apicid : 30
fpu : yes
fpu_exception : yes
cpuid level : 15
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm abm cpuid_fault epb invpcid_single tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm xsaveopt cqm_llc cqm_occup_llc dtherm ida arat pln pts
bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
bogomips : 4800.03
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
power management:
在 turbo 模式下硬件限制为 3.2 Ghz（如图所示cpupower）：
analyzing CPU 15:
driver: intel_pstate
CPUs which run at the same hardware frequency: 15
CPUs which need to have their frequency coordinated by software: 15
maximum transition latency: Cannot determine or is not supported.
hardware limits: 1.20 GHz - 3.20 GHz
available cpufreq governors: performance powersave
current policy: frequency should be within 1.20 GHz and 3.20 GHz.
The governor "performance" may decide which speed to use
within this range.
current CPU frequency: Unable to call hardware
current CPU frequency: 2.85 GHz (asserted by call to kernel)
boost state support:
Supported: yes
Active: yes
我创建了一个小脚本来在一个核心上产生高负载并用它检查其频率cpupower -c 15 frequency-info -f -m，它确实达到了 3.2 Ghz。
但是，在所有核心上运行脚本时，每个核心的频率不知何故被限制在 2.6 Ghz。
瓶颈在哪里？电源管理策略performance无处不在。