[jira] [Assigned] (GEODE-9002) Add Statistic for /proc/schedstat

["Bill Burcham (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GEODE-9002?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bill Burcham reassigned GEODE-9002:
-----------------------------------

    Assignee: Bill Burcham

> Add Statistic for /proc/schedstat
> ---------------------------------
>
>                 Key: GEODE-9002
>                 URL: https://issues.apache.org/jira/browse/GEODE-9002
>             Project: Geode
>          Issue Type: New Feature
>          Components: statistics
>            Reporter: Bill Burcham
>            Assignee: Bill Burcham
>            Priority: Major
>
> Linux performance icon Brendan Gregg advocates the [USE|http://www.brendangregg.com/usemethod.html] method of performance analysis: Utilization Saturation and Errors.
> When it comes to CPU, Geode captures a number of _utilization_ statistics. Some are direct like LinuxSystemStats cpuIdle and cpuActive. Others are indirect like:
>  
> But utilization statistics alone can't tell you when a resource (like CPU) is _saturated_, i.e. when  demand is higher than the servicing ability. If you're just looking at utilization metrics, then a saturated system might look a lot like a system just below saturation. In order to tell the difference, saturation metrics are needed.
> In the case of CPU, there is a conceptual queue in front of each processor. Tasks (operating system threads) that are ready to run, enter a queue, and after some delay, are given a time slice by an actual physical CPU.
> You might think that Geode's LinuxSystemStats loadAverage1 and 5 and 15, might fit this bill. Those statistics do provide some saturation information. The problem is, they conflate CPU with I/O and other things (see [Linux Load Averages: Solving the Mystery|[http://www.brendangregg.com/blog/2017-08-08/linux-load-averages.html].)]
> A better, more specific measure of CPU saturation is available through statistics exposed via the /proc/schedstat virtual file.
> When this ticket is complete, there will be a new statistic type called LinuxThreadScheduler, with three associated statistics gathered directly from /proc/schedstat or derived from data gathered from it:
>  * runningTimeNanos: sum of all time spent running by tasks on this processor in nanoseconds
>  * queuedTimeNanos: sum of all time spent waiting to run by tasks on this processor in nanoseconds
>  * tasksScheduledCount: # of tasks (not necessarily unique) given to the processor
>  * meanTaskQueuedTimeNanos: average time that a ready-to-run task waited for a CPU, since the last sample, in nanoseconds
> One "statistic" will be gathered for each CPU. So a Geode process running on a two-CPU system will capture two statistics, called "cpu0", "cpu1", each of this new type.
> By default Geode will not gather these new statistics. A TBD Java system property will be used to enable gathering the new LinuxThreadScheduler statistic.



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