[Bugs] [Bug 1695480] New: Global Thread Pool

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1695480

            Bug ID: 1695480
           Summary: Global Thread Pool
           Product: GlusterFS
           Version: mainline
            Status: NEW
         Component: core
          Assignee: bugs at gluster.org
          Reporter: jahernan at redhat.com
                CC: bugs at gluster.org
  Target Milestone: ---
    Classification: Community



Description of problem:

The Global Thread Pool provides lower contention and increased performance in
some cases, but it has been observed that sometimes there's a huge increment in
the number of requests going to the disks in parallel which seems to be causing
a performance degradation.

Actually, it seems that sending the same amount of requests but from fewer
threads is giving higher performance.

The current implementation already does some dynamic adjustment of the number
of active threads based on the current number of requests, but it doesn't
consider the load on the back-end file systems. This means that as long as more
requests come, the number of threads is scaled accordingly, which could have a
negative impact if the back-end is already saturated.

The way to control that in current version is to manually adjust the maximum
number of threads that can be used, which effectively limits the load on
back-end file systems even if more requests are coming, but this is only useful
for volumes whose workload is homogeneous and constant.

To make it more versatile, the maximum number of threads need to be
automatically self-adjusted to adapt dynamically to the current load so that it
can be useful in a general case.

Version-Release number of selected component (if applicable): mainline


How reproducible:


Steps to Reproduce:
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Actual results:


Expected results:


Additional info:

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