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