如何查找物理cpu，cpu核心和逻辑cpu的数量

环境

• Red Hat Enterprise Linux 4
• Red Hat Enterprise Linux 5
• Red Hat Enterprise Linux 6
• Red Hat Enterprise Linux 7

问题

• x86 / x86_64系统上的物理CPU，CPU内核和逻辑CPU之间有什么区别？
• 如何从RHEL操作系统获取可用处理器列表?

决议

• 物理CPU数量

  • 下面的命令将显示一个系统有多少活动的物理处理器。例如:如果这个数字是2，则可以打开系统机箱，用手删除2个物理处理器。

     

    $ grep physical.id /proc/cpuinfo | sort -u | wc -l
    2

• 每个CPU的核心数

  • 在具有多核处理器的系统上，下面的命令应该报告每个物理处理器的CPU内核数量(尽管在极少数情况下可能不会)。例如:如果这个数字是4，而物理CPU是2，那么这2个物理处理器中的每个都有4个CPU内核，总共有8个内核。

     

    $ grep cpu.cores /proc/cpuinfo | sort -u
    cpu cores : 4

• 逻辑处理器数量

  • 最后这个命令将显示Linux内核所看到的“逻辑”处理器的总数。这个数字通常是三个统计数据中最重要的。它是处理器的有效数量——就操作系统而言，这是能够在任何给定微秒内工作的不同cpu的数量。示例:继续上面的示例场景，下面看到的数字可以是16而不是8。简单地说，如果这个命令显示的数字与CPU内核的总数不同，这是因为在CPU上启用了超线程，从而进一步划分了每个内核(在本例中，分为两个可用的“线程”)。

     

    $ grep processor /proc/cpuinfo | wc -l
    16

许可?

• 为了确定RHEL许可原因的cpu数量，上面的第一个命令就足够了;但是，要进行更多的讨论，请咨询 如何确定系统上的CPU插槽数

• 如果购买的许可根据插槽（已填充或未填充），处理器或内核的数量而变化的第三方软件，请与软件供应商联系，以确切了解它们如何计算CPU数量。

工具

• 注意，Red Hat Enterprise Linux 6和7附带了lscpu命令，该命令可以打印出系统处理器的简单可读摘要。此外，在RHEL6中，hwloc包是可用的(RHEL7附带它)——hwloc包括lstopo命令，以及各种hwloc-*命令。

• 在RHEL6之前，直接检查/proc/cpuinfo(如上所述)或使用x86info或dmidecode命令(同名rpm)都能查到相同的信息。

• 其他第三方选项没有提供担保:xsos(由本文的原始作者开发)和lshw(可在EPEL中获得)。

• 对于任何版本的Red Hat Enterprise Linux:本文附带的BASH脚本都会解析/proc/cpuinfo，以打印如下所示的易于阅读的摘要。(注意，它没有提供任何保证或官方支持。)
  Raw

  $ cpu
  128 logical processors (64 CPU cores)
  8 Intel Xeon CPU X7560 @ 2.27GHz (flags: constant_tsc,ht,lm,pae,vmx)
  └─16 threads / 8 cores each

   1 #!/bin/bash
   2 #
   3 # This simple script uses /proc/cpuinfo (or filename of your choosing) to print
   4 # a succinct summary about a system's processors.
   5 # Other useful utilities (some only available in RHEL6 or EPEL):
   6 #   x86info, dmidecode, lscpu, cpuid, lshw, lstopo, xsos
   7 #
   8 # Originally uploaded to redhat.com by Ryan Sawhill <rsaw@redhat.com>, Sep 2012; Updated Jan 2013
   9 # This code is from xsos, which can do so much more <http://github.com/ryran/xsos>
  10 #
  11
  12 # Get input
  13 if [[ -r $1 && -f $1 ]]; then
  14   # If passed a readable file, use that
  15   cpuinfo=$1
  16 else
  17   # Otherwise, use /proc/cpuinfo
  18   cpuinfo=/proc/cpuinfo
  19 fi
  20
  21 # Get model of cpu
  22 model_cpu=$(awk -F: '/^model name/{print $2; exit}' <"$cpuinfo")
  23
  24 # If no model detected (e.g. on Itanium), try to use vendor+family
  25 [[ -z $model_cpu ]] && {
  26   vendor=$(awk -F: '/^vendor /{print $2; exit}' <"$cpuinfo")
  27   family=$(awk -F: '/^family /{print $2; exit}' <"$cpuinfo")
  28   model_cpu="$vendor$family"
  29 }
  30
  31 # Clean up cpu model string
  32 model_cpu=$(sed -e 's,(R),,g' -e 's,(TM),,g' -e 's,  *, ,g' -e 's,^ ,,' <<<"$model_cpu")
  33
  34 # Get number of logical processors
  35 num_cpu=$(awk '/^processor/{n++} END{print n}' <"$cpuinfo")
  36
  37 # Get number of physical processors
  38 num_cpu_phys=$(grep '^physical id' <"$cpuinfo" | sort -u | wc -l)
  39
  40 # If "physical id" not found, we cannot make any assumptions (Virtualization--)
  41 # But still, multiplying by 0 in some crazy corner case is bad, so set it to 1
  42 # If num of physical *was* detected, add it to the beginning of the model string
  43 [[ $num_cpu_phys == 0 ]] && num_cpu_phys=1 || model_cpu="$num_cpu_phys $model_cpu"
  44
  45 # If number of logical != number of physical, try to get info on cores & threads
  46 if [[ $num_cpu != $num_cpu_phys ]]; then
  47
  48   # Detect number of threads (logical) per cpu
  49   num_threads_per_cpu=$(awk '/^siblings/{print $3; exit}' <"$cpuinfo")
  50
  51   # Two possibile ways to detect number of cores
  52   cpu_cores=$(awk '/^cpu cores/{print $4; exit}' <"$cpuinfo")
  53   core_id=$(grep '^core id' <"$cpuinfo" | sort -u | wc -l)
  54
  55   # The first is the most accurate, if it works
  56   if [[ -n $cpu_cores ]]; then
  57     num_cores_per_cpu=$cpu_cores
  58
  59   # If "cpu cores" doesn't work, "core id" method might (e.g. Itanium)
  60   elif [[ $core_id -gt 0 ]]; then
  61     num_cores_per_cpu=$core_id
  62   fi
  63
  64   # If found info on cores, setup core variables for printing
  65   if [[ -n $num_cores_per_cpu ]]; then
  66     cores1="($((num_cpu_phys*num_cores_per_cpu)) CPU cores)"
  67     cores2=" / $num_cores_per_cpu cores"
  68   # If didn't find info on cores, assume single-core cpu(s)
  69   else
  70     cores2=" / 1 core"
  71   fi
  72
  73   # If found siblings (threads), setup the variable for the final line
  74   [[ -n $num_threads_per_cpu ]] &&
  75     coresNthreads="\n└─$num_threads_per_cpu threads${cores2} each"
  76 fi
  77
  78 # Check important cpu flags
  79 # pae=physical address extensions  *  lm=64-bit  *  vmx=Intel hw-virt  *  svm=AMD hw-virt
  80 # ht=hyper-threading  *  aes=AES-NI  *  constant_tsc=Constant Time Stamp Counter
  81 cpu_flags=$(egrep -o "pae|lm|vmx|svm|ht|aes|constant_tsc" <"$cpuinfo" | sort -u | sed ':a;N;$!ba;s/\n/,/g')
  82 [[ -n $cpu_flags ]] && cpu_flags="(flags: $cpu_flags)"
  83
  84 # Check kernel version; print warning if Xen
  85 [[ $(uname -r) =~ xen ]] && {
  86   echo "Warning: kernel for localhost detected as $(uname -r)"
  87   echo "With Xen, CPU layout in /proc/cpuinfo will be inaccurate; consult dmidecode"
  88 }
  89
  90 # Print out the deets
  91 echo -e "${num_cpu} logical processors ${cores1}"
  92 echo -e "${model_cpu} ${cpu_flags} ${coresNthreads}"

  cpu.sh