在我的 CPU 图表中，我最近注意到，在编译东西时，我似乎永远无法达到 100% 使用率，它只是在最大 60-70% 左右上下波动。
例子：
相比之下，当在我的工作计算机上完成时，该图是完全不透明的。
我想弄清楚这一点并正在使用压力实用程序来模拟 CPU 使用情况，以及 vmstat 来观察。我的 CPU 核心数范围为 1 到 15（我的 CPU 有 12 个逻辑核心），运行压力很大。结果如下，第 1 行对应 1 个运行 100% 的核心，第 2 行对应 2 个核心，依此类推：
procs -----------------------memory---------------------- ---swap-- -----io---- -system-- --------cpu--------
r b swpd free buff cache si so bi bo in cs us sy id wa st
1 0 0 24455180 465548 2862716 0 0 0 38 944 3184 11 1 88 0 0
3 0 0 24508640 465552 2862684 0 0 0 196 1112 2841 18 1 81 0 0
3 0 0 24556876 465564 2865096 0 0 0 63 1880 4569 30 1 70 0 0
4 0 0 24624764 465576 2865044 0 0 0 11 1414 1005 34 0 66 0 0
5 0 0 24625228 465580 2865068 0 0 0 9 1603 1029 42 0 58 0 0
6 0 0 24763772 465600 2864912 0 0 1 159 1973 1032 51 0 49 0 0
8 0 0 24786696 465600 2864844 0 0 0 9 2460 751 56 0 44 0 0
8 0 0 24805572 465600 2864864 0 0 0 78 2619 808 61 0 38 0 0
10 0 0 24811064 465604 2864852 0 0 0 50 2532 761 56 0 44 0 0
14 0 0 24809904 465616 2865180 0 0 0 4 2823 1049 63 0 37 0 0
13 0 0 24868936 465620 2865116 0 0 0 76 2596 709 57 0 43 0 0
19 0 0 24910408 465628 2866136 0 0 0 12 2526 738 56 0 44 0 0
16 0 0 24914768 465636 2865244 0 0 0 36 2757 720 62 0 38 0 0
18 0 0 24914332 465644 2865256 0 0 0 3 2629 862 59 0 41 0 0
19 0 0 24945952 465648 2866224 0 0 0 33 2642 678 59 0 41 0 0
我运行的脚本：
for corecount in $(seq 15); do
stress -c $corecount >/dev/null&
sleep 1
vmstat -w 4 2 | tail -1
pkill stress
sleep 1
done
通过查看该us专栏，我发现 CPU 使用率按预期线性增加，最多达到 6-8 个逻辑核心，但之后它遇到了其他一些瓶颈。鼠标光标此时开始滞后，如果我尝试在 videp 播放器运行时运行，它也会在此时开始卡顿。 （为了进行比较，这是在我的工作计算机上完成的完全相同的测试：http://pastebin.com/MHPSR4E0。这里 cpu 使用率只是线性上升到 99/100 并保持在那里（饱和度在第 8 行，因为它是 8 核 cpu））
（这是整个测试运行的 cpu 图，阻塞点可见
：）
一般信息：
Ubuntu 16.04 LTS，32 GB 内存，i7-5820K 6 核 CPU。
自由-h
total used free shared buff/cache available
Mem: 31G 4,8G 23G 90M 3,3G 26G
Swap: 15G 0B 15G
/proc/cpu信息
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 63
model name : Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz
stepping : 2
microcode : 0x2d
cpu MHz : 1236.339
cache size : 15360 KB
physical id : 0
siblings : 12
core id : 0
cpu cores : 6
apicid : 0
initial apicid : 0
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 aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm ida arat pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm xsaveopt cqm_llc cqm_occup_llc
bugs :
bogomips : 6599.39
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
power management:
[...]
processor : 11
vendor_id : GenuineIntel
cpu family : 6
model : 63
model name : Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz
stepping : 2
microcode : 0x2d
cpu MHz : 1200.246
cache size : 15360 KB
physical id : 0
siblings : 12
core id : 5
cpu cores : 6
apicid : 11
initial apicid : 11
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 aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm ida arat pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm xsaveopt cqm_llc cqm_occup_llc
bugs :
bogomips : 6599.39
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
power management:
lspci
00:00.0 Host bridge: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DMI2 (rev 02)
00:01.0 PCI bridge: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCI Express Root Port 1 (rev 02)
00:01.1 PCI bridge: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCI Express Root Port 1 (rev 02)
00:02.0 PCI bridge: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCI Express Root Port 2 (rev 02)
00:02.2 PCI bridge: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCI Express Root Port 2 (rev 02)
00:02.3 PCI bridge: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCI Express Root Port 2 (rev 02)
00:03.0 PCI bridge: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCI Express Root Port 3 (rev 02)
00:05.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Address Map, VTd_Misc, System Management (rev 02)
00:05.1 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Hot Plug (rev 02)
00:05.2 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 RAS, Control Status and Global Errors (rev 02)
00:05.4 PIC: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 I/O APIC (rev 02)
00:11.0 Unassigned class [ff00]: Intel Corporation C610/X99 series chipset SPSR (rev 05)
00:14.0 USB controller: Intel Corporation C610/X99 series chipset USB xHCI Host Controller (rev 05)
00:16.0 Communication controller: Intel Corporation C610/X99 series chipset MEI Controller #1 (rev 05)
00:19.0 Ethernet controller: Intel Corporation Ethernet Connection (2) I218-V (rev 05)
00:1a.0 USB controller: Intel Corporation C610/X99 series chipset USB Enhanced Host Controller #2 (rev 05)
00:1b.0 Audio device: Intel Corporation C610/X99 series chipset HD Audio Controller (rev 05)
00:1c.0 PCI bridge: Intel Corporation C610/X99 series chipset PCI Express Root Port #1 (rev d5)
00:1c.4 PCI bridge: Intel Corporation C610/X99 series chipset PCI Express Root Port #5 (rev d5)
00:1d.0 USB controller: Intel Corporation C610/X99 series chipset USB Enhanced Host Controller #1 (rev 05)
00:1f.0 ISA bridge: Intel Corporation C610/X99 series chipset LPC Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation C610/X99 series chipset 6-Port SATA Controller [AHCI mode] (rev 05)
00:1f.3 SMBus: Intel Corporation C610/X99 series chipset SMBus Controller (rev 05)
06:00.0 VGA compatible controller: NVIDIA Corporation GF104 [GeForce GTX 460] (rev a1)
06:00.1 Audio device: NVIDIA Corporation GF104 High Definition Audio Controller (rev a1)
08:00.0 USB controller: ASMedia Technology Inc. ASM1142 USB 3.1 Host Controller
ff:0b.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 R3 QPI Link 0 & 1 Monitoring (rev 02)
ff:0b.1 Performance counters: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 R3 QPI Link 0 & 1 Monitoring (rev 02)
ff:0b.2 Performance counters: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 R3 QPI Link 0 & 1 Monitoring (rev 02)
ff:0c.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Unicast Registers (rev 02)
ff:0c.1 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Unicast Registers (rev 02)
ff:0c.2 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Unicast Registers (rev 02)
ff:0c.3 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Unicast Registers (rev 02)
ff:0c.4 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Unicast Registers (rev 02)
ff:0c.5 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Unicast Registers (rev 02)
ff:0f.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Buffered Ring Agent (rev 02)
ff:0f.1 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Buffered Ring Agent (rev 02)
ff:0f.4 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 System Address Decoder & Broadcast Registers (rev 02)
ff:0f.5 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 System Address Decoder & Broadcast Registers (rev 02)
ff:0f.6 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 System Address Decoder & Broadcast Registers (rev 02)
ff:10.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCIe Ring Interface (rev 02)
ff:10.1 Performance counters: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCIe Ring Interface (rev 02)
ff:10.5 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Scratchpad & Semaphore Registers (rev 02)
ff:10.6 Performance counters: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Scratchpad & Semaphore Registers (rev 02)
ff:10.7 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Scratchpad & Semaphore Registers (rev 02)
ff:12.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Home Agent 0 (rev 02)
ff:12.1 Performance counters: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Home Agent 0 (rev 02)
ff:13.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Target Address, Thermal & RAS Registers (rev 02)
ff:13.1 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Target Address, Thermal & RAS Registers (rev 02)
ff:13.2 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel Target Address Decoder (rev 02)
ff:13.3 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel Target Address Decoder (rev 02)
ff:13.4 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel Target Address Decoder (rev 02)
ff:13.5 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel Target Address Decoder (rev 02)
ff:13.6 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO Channel 0/1 Broadcast (rev 02)
ff:13.7 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO Global Broadcast (rev 02)
ff:14.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel 0 Thermal Control (rev 02)
ff:14.1 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel 1 Thermal Control (rev 02)
ff:14.2 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel 0 ERROR Registers (rev 02)
ff:14.3 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel 1 ERROR Registers (rev 02)
ff:14.6 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO (VMSE) 0 & 1 (rev 02)
ff:14.7 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO (VMSE) 0 & 1 (rev 02)
ff:15.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel 2 Thermal Control (rev 02)
ff:15.1 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel 3 Thermal Control (rev 02)
ff:15.2 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel 2 ERROR Registers (rev 02)
ff:15.3 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 0 Channel 3 ERROR Registers (rev 02)
ff:16.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 1 Target Address, Thermal & RAS Registers (rev 02)
ff:16.6 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO Channel 2/3 Broadcast (rev 02)
ff:16.7 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO Global Broadcast (rev 02)
ff:17.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Integrated Memory Controller 1 Channel 0 Thermal Control (rev 02)
ff:17.4 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO (VMSE) 2 & 3 (rev 02)
ff:17.5 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO (VMSE) 2 & 3 (rev 02)
ff:17.6 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO (VMSE) 2 & 3 (rev 02)
ff:17.7 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 DDRIO (VMSE) 2 & 3 (rev 02)
ff:1e.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Power Control Unit (rev 02)
ff:1e.1 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Power Control Unit (rev 02)
ff:1e.2 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Power Control Unit (rev 02)
ff:1e.3 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Power Control Unit (rev 02)
ff:1e.4 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 Power Control Unit (rev 02)
ff:1f.0 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 VCU (rev 02)
ff:1f.2 System peripheral: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 VCU (rev 02)
/proc/内存信息
MemTotal: 32841924 kB
MemFree: 24244428 kB
MemAvailable: 27418672 kB
Buffers: 478012 kB
Cached: 2622028 kB
SwapCached: 0 kB
Active: 6606180 kB
Inactive: 1240728 kB
Active(anon): 4758584 kB
Inactive(anon): 85340 kB
Active(file): 1847596 kB
Inactive(file): 1155388 kB
Unevictable: 8020 kB
Mlocked: 8020 kB
SwapTotal: 16669692 kB
SwapFree: 16669692 kB
Dirty: 284 kB
Writeback: 0 kB
AnonPages: 4754864 kB
Mapped: 780304 kB
Shmem: 93528 kB
Slab: 346300 kB
SReclaimable: 257036 kB
SUnreclaim: 89264 kB
KernelStack: 22112 kB
PageTables: 109808 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 33090652 kB
Committed_AS: 16302224 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 371016 kB
VmallocChunk: 34358945788 kB
HardwareCorrupted: 0 kB
AnonHugePages: 761856 kB
CmaTotal: 0 kB
CmaFree: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 537784 kB
DirectMap2M: 5648384 kB
DirectMap1G: 29360128 kB
在使用 10 个核心进行压力测试时，来自 ksysguard 的更详细的 CPU 使用情况屏幕截图：
到底是怎么回事？我可以观察内核的哪些其他部分来了解发生了什么？是否有一些 cpu 调度程序配置？它并不总是这样，我绝对确定我之前能够以 100% cpu 利用率进行编译，没有鼠标延迟，并且除了风扇运行之外没有真正注意到它。
答案1
要调试 Linux 上的调度或应用程序性能问题，在perf stat.它报告有关处理器管道、其停滞周期或内存行为的统计信息。
可能出现的问题：
- Linux/调度程序错误
- 英特尔 HT 无法跟上您的线程
- 内存无法为程序提供足够的数据
出于复杂性的考虑，Ubuntu 16.04 的分辨率是错误的/旧内核 (4.2.0)，而不是预期的 4.4.0。更新解决了问题。
答案2
我不认为这是一个问题，而是您正在运行的程序的行为。
您的应用程序（编译）不会执行 100% CPU，它可能会执行相当多的 IO。当应用程序进行 IO 时，它会进入 iowait 模式。在完成 IO 操作之前，它无法使用 CPU。
请注意 中的“等待时间” top。