[jira] [Created] (QPID-7895) [linearstore] Excessive CPU utilization for some kernel clocksources

["Kim van der Riet (JIRA)" <ji...@apache.org>]

Kim van der Riet created QPID-7895:
--------------------------------------

             Summary: [linearstore] Excessive CPU utilization for some kernel clocksources
                 Key: QPID-7895
                 URL: https://issues.apache.org/jira/browse/QPID-7895
             Project: Qpid
          Issue Type: Bug
          Components: C++ Broker
            Reporter: Kim van der Riet
            Assignee: Kim van der Riet


For some kernel clocksources (eg acpi_pm), it has been observed that there is an excessively high CPU utilization which correlates with the linearstore's flush timeout being set to a very low value (100us).  This is a problem for some customers which require almost instant flush to obtain pseudo-synchronous store behavior (hence the 100us flush timer) and run many brokers (up to hundreds) on a single machine.  In these cases, the CPU is 100% utilized.

A check of the source shows that the flush timer is firing continuously, irrespective of whether any disk I/O has taken place.

It is proposed that a change to linearstore be made which will only run the timer when needed (ie while there is content in the write buffers that needs flushing).



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@qpid.apache.org
For additional commands, e-mail: dev-help@qpid.apache.org