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<p class="MsoNormal">Hi ,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We are observing performance issue with Pulse Audio in our embedded infotainment platform.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">To brief on the usage of PA in this platform , Pulse Audio is used for Audio routing from an Audio source provider to another Audio Source sink using Pulse Audio using the Null sink and Null sink.monitor.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The audio path is as below. <o:p></o:p></p>
<p class="MsoNormal">Audio source provider -> Pulse Audio Nullsink (eg. Route_test) -> Pulse Audio Null source (eg. Route_test.monitor) -> Audio router to sink<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">There are two behavioral issues observed in the Pulse Audio , below is the description of the issues.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in"><o:p> </o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>The Audio source provider creates a Pulse stream and writes to the Pulse Audio Nullsink before the Audio router thread has opened the Pulse Stream for reading from nullsink.monitor . In this condition , from the application Audio router
, PA reader thread opens the PA stream and calls the PA read API , it is blocked for more than 1 sec inside PA read API before the first read is successful.
<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in"><o:p> </o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in">What could cause this delay in the first PA read ? Does the writer starting to write to PA first cause a delay/block on the reader when it eventually becomes active ?<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in"><o:p> </o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>For the same issue above, on further debugging , On the PA reader side , the PA stream open is called and the stream is kept open always by the reader. In this condition , the delay is no longer observed in the first PA read. But this
causes an impact on the CPU.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in">When the PA stream is always open and no reads are done ,significant CPU usage is observed , PA process consumes 21 - 23 % and the threaded-m1 consumes 5 – 7 % CPU even when there is no read/write happening
in PA server. <o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in"><o:p> </o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in">Why is this high CPU observed and how to optimize the CPU , is there any configuration where the PA stream can be opened and still have low CPU consumption ?<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal">Please provide your insights on the two queries.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Thanks & Regards<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Manjula R<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">SME – Audio/DSP<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Visteon Technical & Services Center , India<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Phone: +91-44-<b>4947</b>7829<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="http://www.visteon.com/products/electronics/index.html"><span style="color:windowtext;text-decoration:none"><img border="0" width="474" height="99" id="Picture_x0020_1" src="cid:image001.png@01D0408C.C79CB740"></span></a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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