Module proc_sys_parser::schedstat

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Read data from /proc/schedstat into the struct ProcSchedStat.

The documentation for /proc/schedstat is found here: https://www.kernel.org/doc/Documentation/scheduler/sched-stats.txt. This says the cpu scheduler statistics are in jiffies. THIS IS INCORRECT since kernel version 2.6.23/commit 425e0968a25f. (https://github.com/torvalds/linux/commit/425e0968a25f)

The cpu scheduler statistics are now in nanoseconds.

Here is an example obtaining the data from /proc/schedstat:

use proc_sys_parser::{schedstat, schedstat::ProcSchedStat};

let proc_schedstat = schedstat::read();

println!("{:#?}", proc_schedstat);

Example output:

ProcSchedStat {
    version: 15,
    timestamp: 4294964691,
    cpu: [[0, 0, 0, 0, 0, 0, 0, 40178371330, 4778820750, 26299],
          [1, 0, 0, 0, 0, 0, 0, 35526916030, 3606934630, 20919],
          [2, 0, 0, 0, 0, 0, 0, 29224692150, 5614007710, 28163],
          [3, 0, 0, 0, 0, 0, 0, 23848255950, 2265375620, 26240],
          [4, 0, 0, 0, 0, 0, 0, 33846671420, 2990792870, 25605],
          [5, 0, 0, 0, 0, 0, 0, 34565043670, 2885580430, 22629]],
    domain: [[0, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
             [0, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
             [0, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
             [0, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
             [0, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
             [0, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
}

(edited for readability)

If you want to change the path and/or file that is read for ProcSchedStat, which is /proc/schedstat by default, use:

use proc_sys_parser::{schedstat, schedstat::{ProcSchedStat, Builder}};

let proc_schedstat = Builder::new().path("/myproc").read();

§cpu vector numbers

A /proc/schedstat cpu line might look like this:

cpu0 0 0 0 0 0 0 4017837133 477882075 26299

Such a line will be transformed to the following (Vec<u64>) vector in ProcSchedStat.cpu:

[0, 0, 0, 0, 0, 0, 0, 40178371330, 4778820750, 26299]

The first number is the cpu number (cpu0), the other numbers for cpu statistics follow. This has the consequence that the CPU statistics field numbers in the description from kernel.org now have to be increased by one to find the statistic in the vector.

Also mind that:

  • The time running on cpu in jiffies, statistic number 7 in the description at kernel.org is changed to time in milliseconds in the 8th position in the vector.
  • The time waiting to run in jiffies, statistic number 8 in the description at kernel.org is changed to time in milliseconds in the 9th position in the vector.

§domain vector numbers

A /proc/schedstat domain line might look like this:

domain0 3f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Such a line will be transformed to the following (Vec<u64>) vector in ProcSchedStat.domain:

[0, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

The first number is the domain number (domain0). The second number is the decimal representation of the hexadecimal 3f number representing the cpu mask. Starting from the third number, the statistics that are explained with the Domain statistics are available. This has the consequence that the field numbers in the kernel.org explanation have to be increased by two to match the statistic in the vector.

Structs§

Functions§

  • read
    The main function for building a ProcSchedStat struct with current data. This uses the Builder pattern, which allows settings such as the filename to specified.