我有一台联想 Ideapad 720s 14,配备英特尔 i7-8850U CPU,使用 Ubuntu 17.10 和内核 4.13.0-31-generic。我使用 i7z 来测量时钟速度。我的 CPU 拒绝加速超过 1.8GHz(其基本频率),即使在具有大量热余量的单线程工作负载下也是如此。其最大 Turbo 速度宣传为 4GHz。
当所有四个核心都处于活动状态时,保持 1.8GHz 的频率没有问题,尽管风扇噪音更大,因此节流不是问题。使用所有核心还可以将性能完美提升 4 倍,因此时钟速度测量似乎是正确的。
以下是运行单线程工作负载时 i7z 的输出:
True Frequency (without accounting Turbo) 1992 MHz
CPU Multiplier 20x || Bus clock frequency (BCLK) 99.60 MHz
Socket [0] - [physical cores=4, logical core918, max online cores ever=4]
TURBO ENABLED on 4 Cores, Hyper Threading ON 55
Max Frequency without considering Turbo 2091.60 MHz (99.60 x [21])
Max TURBO Multiplier (if Enabled) with 1/2/3/4 Cores is 40x/40x/37x/37x
Real Current Frequency 1339.86 MHz [99.60 x 13.45] (Max of below)
Core [core-id] :Actual Freq (Mult.)90.55 C0% Ha55(C1)% C3 % C6 % Temp VCore
Core 1 [0]: 1339.86 (13.45x) 3.48 95.7 0 2 48 0.6167
Core 2 [1]: 1796.17 MHz [99.55 x 18.04] (Max of below) 0 47 0.6165
Core 3 [2]: 1041.68 (10.46x) 2.08 88.4 0 10.5 47 0.6162
Core 4 [3]: 1796.17 (18.04x) 1 97.5 1 1 49 0.7679
1795.63 (18.04x) 1.37 97.1 0 1.66 47 0.7679
1795.79 (18.04x) 1.84 98.3 0 0 51 0.7679
1795.84 (18.04x) 1.64 96.5 1 1 47 0.7679
C0 = Processor running without halting
C1 = Processor running with halts (States >C0 are power saver modes with cores idling)
C3 = Cores running with PLL turned off and core cache turned off
C6, C7 = Everything in C3 + core state saved to last level cache, C7 is deeper than C6
Above values in table are in percentage over the last 1 sec
温度适中(约 50C),风扇转速远未达到全速。不过,核心从未尝试过加速至 1.8GHz 以上。Turbo Boost 在 Windows 中可以正常工作,尽管它在那里表现得有些不稳定(如果这相关的话)。
lscpu | grep MHz
输出:
CPU MHz: 2000.000
CPU max MHz: 1800,0000
CPU min MHz: 400,0000
sudo lshw -c cpu
输出(省略部分内容):
*-cpu
description: CPU
product: Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz
vendor: Intel Corp.
physical id: 4
bus info: cpu@0
version: Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz
serial: To Be Filled By O.E.M.
slot: U3E1
size: 1800MHz
capacity: 4005MHz
width: 64 bits
clock: 100MHz
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编辑: cat /sys/devices/system/cpu/intel_pstate/no_turbo
输出:
0