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c-user: Add SMP profiling

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Sebastian Huber 2017-02-03 13:58:19 +01:00
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c-user/symmetric_multiprocessing_services.rst
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.. COMMENT: COPYRIGHT (c) 2014.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: Copyright (c) 2017 embedded brains GmbH.
.. COMMENT: All rights reserved.
Symmetric Multiprocessing (SMP)
@ -599,6 +600,63 @@ processors.
:width: 400
:align: center
Profiling
---------
To identify the bottlenecks in the system, support for profiling of low-level
synchronization is optionally available. The profiling support is a BSP build
time configuration option (``--enable-profiling``) and is implemented with an
acceptable overhead, even for production systems. A low-overhead counter for
short time intervals must be provided by the hardware.
Profiling reports are generated in XML for most test programs of the RTEMS
testsuite (more than 500 test programs). This gives a good sample set for
statistics. For example the maximum thread dispatch disable time, the maximum
interrupt latency or lock contention can be determined.
.. code-block:: xml
<ProfilingReport name="SMPMIGRATION 1">
<PerCPUProfilingReport processorIndex="0">
<MaxThreadDispatchDisabledTime unit="ns">36636</MaxThreadDispatchDisabledTime>
<MeanThreadDispatchDisabledTime unit="ns">5065</MeanThreadDispatchDisabledTime>
<TotalThreadDispatchDisabledTime unit="ns">3846635988
</TotalThreadDispatchDisabledTime>
<ThreadDispatchDisabledCount>759395</ThreadDispatchDisabledCount>
<MaxInterruptDelay unit="ns">8772</MaxInterruptDelay>
<MaxInterruptTime unit="ns">13668</MaxInterruptTime>
<MeanInterruptTime unit="ns">6221</MeanInterruptTime>
<TotalInterruptTime unit="ns">6757072</TotalInterruptTime>
<InterruptCount>1086</InterruptCount>
</PerCPUProfilingReport>
<PerCPUProfilingReport processorIndex="1">
<MaxThreadDispatchDisabledTime unit="ns">39408</MaxThreadDispatchDisabledTime>
<MeanThreadDispatchDisabledTime unit="ns">5060</MeanThreadDispatchDisabledTime>
<TotalThreadDispatchDisabledTime unit="ns">3842749508
</TotalThreadDispatchDisabledTime>
<ThreadDispatchDisabledCount>759391</ThreadDispatchDisabledCount>
<MaxInterruptDelay unit="ns">8412</MaxInterruptDelay>
<MaxInterruptTime unit="ns">15868</MaxInterruptTime>
<MeanInterruptTime unit="ns">3525</MeanInterruptTime>
<TotalInterruptTime unit="ns">3814476</TotalInterruptTime>
<InterruptCount>1082</InterruptCount>
</PerCPUProfilingReport>
<!-- more reports omitted --->
<SMPLockProfilingReport name="Scheduler">
<MaxAcquireTime unit="ns">7092</MaxAcquireTime>
<MaxSectionTime unit="ns">10984</MaxSectionTime>
<MeanAcquireTime unit="ns">2320</MeanAcquireTime>
<MeanSectionTime unit="ns">199</MeanSectionTime>
<TotalAcquireTime unit="ns">3523939244</TotalAcquireTime>
<TotalSectionTime unit="ns">302545596</TotalSectionTime>
<UsageCount>1518758</UsageCount>
<ContentionCount initialQueueLength="0">759399</ContentionCount>
<ContentionCount initialQueueLength="1">759359</ContentionCount>
<ContentionCount initialQueueLength="2">0</ContentionCount>
<ContentionCount initialQueueLength="3">0</ContentionCount>
</SMPLockProfilingReport>
</ProfilingReport>
Scheduler Helping Protocol
--------------------------