Differential file position of process.


Home Forum Introducing lxtx – One tool for observing Linux Performance Differential file position of process.

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    Dave
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    lxtx collects each process performance data from files in /proc/[PID]/.
    This directory also has fdinfo, and lxtx uses this information to collect differential position of opened file.
    This value might be usually how much sequential read or write is going on, even though this differential value represents just change of file position per unit time.

    Below is example during file upload by sftp. Meanwhile, network traffic is 2.5MBPS to be read, and the differential file position is 2.39MBPS.

    PID PPID USER S CPU USR SYS CHAR SYSC BYTES MajFlt START_TIME Size Pin RSS Data Stack Lib Swap THRD Command
    30993 1661 root S 11.30 0.98 10.31 4.80M 823.7 0 0 16.11.17 15:05:19 99.4M 0 5.69M 2.02M 88.00K 7.73M 0 1 sshd: root@notty
    31000 30993 root S 5.40 0 5.40 4.78M 602.2 2.39M 0 16.11.17 15:05:19 56.66M 0 2.92M 800.0K 88.00K 7.35M 0 1 /usr/libexec/openssh/sftp-server
    –> File : fd 5(Delta Rate : 2.39M / Flags : 0100001) owned by sftp-server[31000/30993] /vg/vg02/lvol2/dummy.dat

    I/F_name IPAddress RBytes WBytes RPkts WPkts RErr WErr RDrop WDrop Coll
    Total 2.50M 75.39K 1.91K 443.0 0 0 0 0 0
    eth0 192.168.29.66 2.50M 75.39K 1.91K 443.0 0 0 0 0 0

    Above result can be obtained by ./lxtx -n 5 -p 10 -f
    -n 5 : At most, 5 network interface entries.
    -p 10 : At most, 10 process entries
    -f : process entries include differential file position data

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