在Linux下,如何发现哪个进程使用交换空间更多?


当前回答

下面是一个与@loolotux脚本输出相同的版本,但速度要快得多(但可读性较差)。 在我的机器上,这个循环大约需要10秒,我的版本需要0.019秒,这对我来说很重要,因为我想把它变成一个cgi页面。

    join -t / -1 3 -2 3 \
    <(grep VmSwap /proc/*/status  |egrep -v '/proc/self|thread-self' | sort -k3,3 --field-separator=/ ) \
    <(grep -H  '' --binary-files=text /proc/*/cmdline |tr '\0' ' '|cut -c 1-200|egrep -v '/proc/self|/thread-self'|sort -k3,3 --field-separator=/ ) \
    | cut -d/ -f1,4,7- \
    | sed 's/status//; s/cmdline//' \
    | sort -h -k3,3 --field-separator=:\
    | tee >(awk -F: '{s+=$3} END {printf "\nTotal Swap Usage = %.0f kB\n",s}') /dev/null

其他回答

运行top,然后按OpEnter。现在进程应该根据它们的交换使用情况进行排序。

这是一个更新,因为我原来的答案没有提供一个确切的答案,在评论中指出的问题。从htop常见问题:

It is not possible to get the exact size of used swap space of a process. Top fakes this information by making SWAP = VIRT - RES, but that is not a good metric, because other stuff such as video memory counts on VIRT as well (for example: top says my X process is using 81M of swap, but it also reports my system as a whole is using only 2M of swap. Therefore, I will not add a similar Swap column to htop because I don't know a reliable way to get this information (actually, I don't think it's possible to get an exact number, because of shared pages).

这是我的一句话:

cat /proc/*/status | grep -E 'VmSwap:|Name:' | grep VmSwap -B1 | cut -d':' -f2 | grep -v '\-\-' | grep -o -E '[a-zA-Z0-9]+.*$' | cut -d' ' -f1 | xargs -n2 echo | sort -k2 -n

这一行的步骤是:

Get all the data in /proc/process/status for all processes Select the fields VmSwap and Name for each Remove the processes that don't have the VmSwap field Remove the names of the fields (VmSwap: and Name:) Remove lines with -- that were added by the previous step Remove the spaces at the start of the lines Remove the second part of each process name and " kB" after the swap usage number Take name and number (process name and swap usage) and put them in one line, one after the other Sort the lines by the swap usage

不完全清楚您的意思是要找到交换出最多页的进程还是导致交换出最多页的进程。

对于前者,您可以运行top并按swap排序(按'Op'),对于后者,您可以运行vmstat并查找'so'的非零条目。

自2015年内核补丁添加SwapPss (https://lore.kernel.org/patchwork/patch/570506/)以来,人们终于可以得到成比例的交换计数,这意味着如果一个进程交换了很多,然后它分叉,两个分叉的进程将分别报告交换50%。如果其中一个发生分叉,每个进程被计算为交换页面的33%,所以如果你把所有的交换使用量计算在一起,你得到的是真实的交换使用量,而不是数值乘以进程数。

简而言之:

(cd /proc; for pid in [0-9]*; do printf "%5s %6s %s\n" "$pid" "$(awk 'BEGIN{sum=0} /SwapPss:/{sum+=$2} END{print sum}' $pid/smaps)" "$(cat $pid/comm)"; done | sort -k2n,2 -k1n,1)

第一列是pid,第二列是KiB中的交换使用情况,其余一行是正在执行的命令。相同的交换计数按pid排序。

上面可能会发出这样的行

awk: cmd. line:1: fatal: cannot open file `15407/smaps' for reading (No such file or directory)

这仅仅意味着pid为15407的进程在/proc/的列表中看到它和读取进程smaps文件之间结束。如果这对您来说很重要,只需在末尾添加2>/dev/null即可。请注意,您可能还会丢失任何其他可能的诊断。

在现实世界的示例案例中,这改变了其他报告在一台服务器上运行的每个apache子服务器使用约40 MB交换空间的工具,而每个子服务器实际使用7-3630 KB交换空间。

另一种在shell中避免循环的脚本变体:

#!/bin/bash
grep VmSwap /proc/[0-9]*/status | awk -F':' -v sort="$1" '
  {
    split($1,pid,"/") # Split first field on /
    split($3,swp," ") # Split third field on space
    cmdlinefile = "/proc/"pid[3]"/cmdline" # Build the cmdline filepath
    getline pname[pid[3]] < cmdlinefile # Get the command line from pid
    swap[pid[3]] = sprintf("%6i %s",swp[1],swp[2]) # Store the swap used (with unit to avoid rebuilding at print)
    sum+=swp[1] # Sum the swap
  }
  END {
    OFS="\t" # Change the output separator to tabulation
    print "Pid","Swap used","Command line" # Print header
    if(sort) {
      getline max_pid < "/proc/sys/kernel/pid_max"
      for(p=1;p<=max_pid;p++) {
        if(p in pname) print p,swap[p],pname[p] # print the values
      }
    } else {
      for(p in pname) { # Loop over all pids found
        print p,swap[p],pname[p] # print the values
      }
    }
    print "Total swap used:",sum # print the sum
  }'

标准用法是script.sh以随机顺序获取每个程序的使用情况(直到awk如何存储其哈希值)或script.sh 1以pid对输出进行排序。

我希望我已经对代码进行了足够的注释,以说明它的功能。