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How to get runque from libperfstat?

  • 1.  How to get runque from libperfstat?

    Posted Mon September 23, 2019 10:46 PM

    Originally posted by: CK_


    I tried to obtain "runque" values from libperfstat.


    I get two pattern of value, both are different from the value of vmstat.
    How can I get the value equivalent to vmstat(r)?

     

    1. perfstat_cpu_total_t:runque
    It is very large as runque length. Also, the result increases monotonically.

    runque = 4769829
    runque = 4769832
    runque = 4769837
    .....

    2. perfstat_cpu_t:runque 
    It is output for each CPU.
    The total value of runque is large than vmstat(r), as follows. 


    name              = cpu0
    runque            = 2

    name              = cpu1
    runque            = 0

    name              = cpu2
    runque            = 0

    name              = cpu3
    runque            = 0

    name              = cpu4
    runque            = 0

    name              = cpu5
    runque            = 0

    name              = cpu6
    runque            = 0

    name              = cpu7
    runque            = 0

    $ vmstat 1 1

    System Configuration: lcpu=8 mem=29824MB

    kthr    memory              page              faults        cpu
    ----- ----------- ------------------------ ------------ -----------
     r  b   avm   fre  re  pi  po  fr   sr  cy  in   sy  cs us sy id wa
     0  0 877859 5321674   0   0   0   0    0   0   9 1252 619  0  0 99  0

    Thank you for your cooperation.

     



  • 2.  RE: How to get runque from libperfstat?

    Posted Tue June 16, 2020 07:06 AM
    You need to take the difference over a period of time and then factor in the run occupancy.

    Below two perfstat_cpu_total_t data structures called cpu_tot_p and cpu_tot_q   ->  the current (p) and previous values (q)

    #define DELTA(member) (cpu_tot_p->member - cpu_tot_q->member)


    if (DELTA(runque) == 0 || DELTA(runocc) == 0)
        pdouble("run_queue", 0.0);
    else
        pdouble("run_queue", ((double)(DELTA(runque))) / ((double)(DELTA(runocc)))); /* fixed */

    I am nosy, what are you actually up to with this cost?
    Perhaps, I have suggestions that could help.
    Cheers Nigel @mr_nmon

    ------------------------------
    Nigel Griffiths
    ------------------------------

    Original Message