Intel微处理器Uncore架构简介

Intel微处理器Uncore架构简介

uncore一词，是英特尔用来描述微处理器中，功能上为非处理器核心（Core）所负担，但是对处理器性能的发挥和维持有必不可少的作用的组成部分。处理器核心（Core）包含的处理器组件都涉及处理器命令的运行，包括算术逻辑单元（ALU）、浮点运算单元（FPU）、一级缓存（L1 Cache）、二级缓存（L2 Cache）。Uncore的功能包括QPI控制器、三级缓存（L3 Cache）、内存一致性监测（snoop agent pipeline）、内存控制器，以及Thunderbolt控制器。至于其余的总线控制器，像是PCI-E、SPI等，则是属于芯片组的一部分。

英特尔Uncore设计根源，来自于北桥芯片。Uncroe的设计是，将对于处理器核心有关键作用的功能重新组合编排，从物理上使它们更靠近核心（集成至处理器芯片上，而它们有部分原来是位于北桥上），以降低它们的访问延时。而北桥上余下的和处理器核心并无太大关键作用的功能，像是PCI-E控制器或者是电源控制单元（PCU），并没有集成至Uncore部分，而是继续作为芯片组的一部分。

具体而言，微架构中的uncore是被细分为数个模块单元的。uncore连接至处理器核心是通过一个叫Cache Box（CBox）的接口实现的，CBox也是末级缓存（Last Level Cache，LLC）的连接接口，同时负责管理缓存一致性。复合的内部与外部QPI链接由物理层单元（Physical Layer units）管理，称为PBox。PBox、CBox以及一个或更多的内置存储器控制器（iMC，作MBox）的连接由系统配置控制器（System Config Controller，作UBox）和路由器（Router，作RBox）负责管理。

从uncore部分移出列表总线控制器，可以更好地促进性能的提升，通过允许uncore的时钟频率（UCLK）运作于基准的2.66GHz，提升至超过超频限制值的3.44GHz，实现性能提升。这种时脉提升使得核心访问关键功能部件（像是存储器控制器）时的延时值更低（典型情况下处理器核心访问DRAM的时间可降低10纳秒或更多）。

Linux会把识别出的Uncore设备列在sysfs中：

# ls -d /sys/devices/uncore_*

PMU Tools 开源项目pmu-tools集成了ucevent(uncore event)的工具，可以查看并跟踪uncore事件。使用ucevnent.py列出支持的uncore events：

cd pmu-tools/ucevent./ucevent.pyCHA (Home Agent) CACHE Events CHA.LLC_DRD_MISS_PCT LLC DRd Miss PercentageCHA (Home Agent) HA (Home Agent) REQUEST Events CHA.PCT_RD_REQUESTS Percent Read Requests CHA.PCT_WR_REQUESTS Percent Write RequestsCHA (Home Agent) INGRESS Events CHA.AVG_INGRESS_DEPTH Average Ingress (from CMS) Depth CHA.AVG_INGRESS_LATENCY Average Ingress (from CMS) Latency CHA.AVG_INGRESS_LATENCY_WHEN_NE Average Latency in Non-Empty Ingress (from CMS) CHA.CYC_INGRESS_BLOCKED Cycles Ingress (from CMS) Blocked CHA.INGRESS_REJ_V_INS Ingress (from CMS) Rejects vs. InsertsCHA (Home Agent) TOR (Table of Requests, pending transactions) Events CHA.AVG_CRD_MISS_LATENCY Average Code Read Latency CHA.AVG_DEMAND_RD_HIT_LATENCY Average Data Read Hit Latency CHA.AVG_DEMAND_RD_MISS_LOCAL_LATENCY Average Data Read Local Miss Latency CHA.AVG_DRD_MISS_LATENCY Average Data Read Miss Latency CHA.AVG_IA_CRD_LLC_HIT_LATENCY Average Code Read Latency CHA.AVG_RFO_MISS_LATENCY Average RFO Latency CHA.AVG_TOR_DRDS_MISS_WHEN_NE Average Data Read Misses in Non-Empty TOR CHA.AVG_TOR_DRDS_WHEN_NE Average Data Reads in Non-Empty TOR CHA.FAST_STR_LLC_HIT Fast String operations CHA.FAST_STR_LLC_MISS Fast String misses CHA.LLC_CRD_MISS_TO_LOC_MEM LLC Code Read Misses to Local Memory CHA.LLC_CRD_MISS_TO_REM_MEM LLC Code Read Misses to Remote Memory CHA.LLC_DRD_MISS_TO_LOC_MEM LLC Data Read Misses to Local Memory CHA.LLC_DRD_MISS_TO_REM_MEM LLC Data Read Misses to Remote Memory CHA.LLC_DRD_PREFETCH_HITS DRd Prefetches that Hit the LLC ...

比如跟踪10秒内不同Socket上的PCI带宽：

# ucevent.py -I 2000 CBO.PCIE_DATA_BYTES sleep 10S0-CBO.PCIE_DATA_BYTES|

再比如跟踪某个应用在内存控制器(iMC)上统计获得的缺页次数，一般情况下，这个指标可以用来衡量内存延时:​​# ucevent.py iMC.PCT_REQUESTS_PAGE_MISS my-workload​​

PCM (Processor Counter Monitor)

PCM提供了一些监控LLC, PCI，QPI的工具。其中，pcm.x可以监控core, cache miss/hit和各个socket的upi带宽：

./pcm.x...Detected Intel(R) Xeon(R) Gold 5118 CPU @ 2.30GHz "Intel(r) microarchitecture codename Skylake-SP" stepping 4 microcode level 0x2000043 EXEC : instructions per nominal CPU cycle IPC : instructions per CPU cycle FREQ : relation to nominal CPU frequency='unhalted clock ticks'/'invariant timer ticks' (includes Intel Turbo Boost) AFREQ : relation to nominal CPU frequency while in active state (not in power-saving C state)='unhalted clock ticks'/'invariant timer ticks while in C0-state' (includes Intel Turbo Boost) L3MISS: L3 (read) cache misses L2MISS: L2 (read) cache misses (including other core's L2 cache *hits*) L3HIT : L3 (read) cache hit ratio (0.00-1.00) L2HIT : L2 cache hit ratio (0.00-1.00) L3MPI : number of L3 (read) cache misses per instruction L2MPI : number of L2 (read) cache misses per instruction READ : bytes read from main memory controller (in GBytes) WRITE : bytes written to main memory controller (in GBytes) L3OCC : L3 occupancy (in KBytes) TEMP : Temperature reading in 1 degree Celsius relative to the TjMax temperature (thermal headroom): 0 corresponds to the max temperature energy: Energy in Joules Core (SKT) | EXEC | IPC | FREQ | AFREQ | L3MISS | L2MISS | L3HIT | L2HIT | L3MPI | L2MPI | L3OCC | TEMP 0 0 0.01 0.37 0.04 1.17 36 K 103 K 0.54 0.63 0.00 0.00 576 47 1 1 0.00 0.88 0.00 1.17 4602 13 K 0.64 0.68 0.00 0.00 432 56 2 0 0.01 0.82 0.01 1.17 20 K 61 K 0.57 0.70 0.00 0.00 384 48 3 1 0.01 0.87 0.01 1.17 16 K 41 K 0.56 0.72 0.00 0.00 2016 57 4 0 0.01 0.78 0.01 1.17 18 K 66 K 0.67 0.66 0.00 0.00 672 49 5 1 0.00 0.51 0.01 1.17 14 K 31 K 0.51 0.62 0.00 0.00 1152 58 6 0 0.01 0.65 0.01 1.17 21 K 72 K 0.65 0.61 0.00 0.00 1968 50 7 1 0.00 0.82 0.00 1.17 6567 13 K 0.45 0.60 0.00 0.00 480 58...Intel(r) UPI data traffic estimation in bytes (data traffic coming to CPU/socket through UPI links): UPI0 UPI1 | UPI0 UPI1--------------------------------------------------------------------------------------------------------------- SKT 0 43 M 43 M | 0% 0% SKT 1 32 M 31 M | 0% 0%---------------------------------------------------------------------------------------------------------------...

pcm.memory.x可以用来监控各个内存通道的读写带宽：

# ./pcm-memory.x Processor Counter Monitor: Memory Bandwidth Monitoring Utility ($Format:%ci ID=%h$) This utility measures memory bandwidth per channel or per DIMM rank in real-timeNumber of physical cores: 24Number of logical cores: 48Number of online logical cores: 48Threads (logical cores) per physical core: 2Num sockets: 2Physical cores per socket: 12Core PMU (perfmon) version: 4Number of core PMU generic (programmable) counters: 4Width of generic (programmable) counters: 48 bitsNumber of core PMU fixed counters: 3Width of fixed counters: 48 bitsNominal core frequency: 2300000000 HzPackage thermal spec power: 105 Watt; Package minimum power: 64 Watt; Package maximum power: 231 Watt;Socket 0: 2 memory controllers detected with total number of 6 channels. 2 QPI ports detected.Socket 1: 2 memory controllers detected with total number of 6 channels. 2 QPI ports detected.Detected Intel(R) Xeon(R) Gold 5118 CPU @ 2.30GHz "Intel(r) microarchitecture codename Skylake-SP" stepping 4 microcode level 0x2000043Update every 1 seconds|---------------------------------------||---------------------------------------||-- Socket 0 --||-- Socket 1 --||---------------------------------------||---------------------------------------||-- Memory Channel Monitoring --||-- Memory Channel Monitoring --||---------------------------------------||---------------------------------------||-- Mem Ch 0: Reads (MB/s): 18.91 --||-- Mem Ch 0: Reads (MB/s): 16.60 --||-- Writes(MB/s): 23.22 --||-- Writes(MB/s): 18.96 --||-- Mem Ch 1: Reads (MB/s): 18.98 --||-- Mem Ch 1: Reads (MB/s): 16.80 --||-- Writes(MB/s): 23.39 --||-- Writes(MB/s): 19.15 --||-- Mem Ch 2: Reads (MB/s): 18.77 --||-- Mem Ch 2: Reads (MB/s): 16.35 --||-- Writes(MB/s): 23.05 --||-- Writes(MB/s): 18.71 --||-- Mem Ch 3: Reads (MB/s): 17.89 --||-- Mem Ch 3: Reads (MB/s): 15.75 --||-- Writes(MB/s): 22.94 --||-- Writes(MB/s): 18.44 --||-- Mem Ch 4: Reads (MB/s): 17.87 --||-- Mem Ch 4: Reads (MB/s): 15.88 --||-- Writes(MB/s): 22.78 --||-- Writes(MB/s): 18.55 --||-- Mem Ch 5: Reads (MB/s): 18.04 --||-- Mem Ch 5: Reads (MB/s): 16.80 --||-- Writes(MB/s): 22.93 --||-- Writes(MB/s): 19.64 --||-- NODE 0 Mem Read (MB/s) : 110.47 --||-- NODE 1 Mem Read (MB/s) : 98.18 --||-- NODE 0 Mem Write(MB/s) : 138.31 --||-- NODE 1 Mem Write(MB/s) : 113.46 --||-- NODE 0 P. Write (T/s): 18728 --||-- NODE 1 P. Write (T/s): 18732 --||-- NODE 0 Memory (MB/s): 248.78 --||-- NODE 1 Memory (MB/s): 211.63 --||---------------------------------------||---------------------------------------||---------------------------------------||---------------------------------------||-- System Read Throughput(MB/s): 208.65 --||-- System Write Throughput(MB/s): 251.77 --||-- System Memory Throughput(MB/s): 460.42 --||---------------------------------------||---------------------------------------|

numa带宽监控

./pcm-numa.x

… Detected Intel® Xeon® Gold 5118 CPU @ 2.30GHz “Intel® microarchitecture codename Skylake-SP” stepping 4 microcode level 0x2000043 Update every 1.0 seconds Time elapsed: 1000 ms Core | IPC | Instructions | Cycles | Local DRAM accesses | Remote DRAM Accesses 0 0.37 30 M 81 M 41 K 90 K 1 0.71 10 M 14 M 90 K 20 K 2 0.64 14 M 22 M 20 K 59 K 3 1.10 79 M 71 M 7264 21 K 4 0.82 26 M 31 M 33 K 48 K 5 0.95 12 M 13 M 8131 27 K 6 0.37 13 M 35 M 306 K 111 K 7 1.00 7417 K 7432 K 9991 9136 8 0.76 12 M 15 M 13 K 6833 9 1.03 14 M 13 M 10 K 19 K 10 0.56 6269 K 11 M 42 K 50 K 11 0.92 26 M 29 M 60 K 85 K 12 0.87 14 M 16 M 17 K 10 K 13 0.64 4130 K 6504 K 5615 40 K 14 0.88 32 M 36 M 57 K 51 K 15 0.88 10 M 11 M 8689 16 K …

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