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<body><div>Hi Don,<br></div>
You should use 48000 sample rate. It is jack's default rate, the recording studio standard and the most tested.<br>Starting with 256 frames 48000 and 2 periods is a good starting setting. If using that produces no xruns then try 128 frames 48000 and 2 or 3 periods next. Then if that produces no xruns, you can go lower.<br><br><div>Preempt (low latency)... False<br></div>
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<div>realTimeConfigQuickScan does this too. I guess that it is because the script is being run by a user that does not have the access level required to probe for that. Best not run that test script as root though. If you have booted kernel-rt (uname -a in a console) then you have low latency. The script just does not try to detect it correctly.<br></div>
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<div>You should add your user account to both the audio and jackuser groups. (su -c 'yum install system-config-users') The program system-config-users will appear in the desktop menu under the administration section afterwards allowing you to do so easily.<br></div>
<div>Be sure to add the threadirqs kernel parameter to the kernel-rt boot entry option in grub.cfg.<br></div>
<div>Install the package rtirq and enable it with: su -c 'yum install rtirq && sytemctl enable rtirq'<br></div>
<div>Edit rtirq so that your sound card's irq is a high priority and not threaded by adding it to RTIRQ_NAME_LIST and RTIRQ_NON_THREADED in rtirq, set limits for the audio and jackuser groups in /etc/security/limits.d/. You set the jackuser group to have a slightly lower rtprio set than the rtprio set for the audio group. <a href="http://subversion.ffado.org/wiki/IrqPriorities">http://subversion.ffado.org/wiki/IrqPriorities</a><br></div>
<div>Set the cpupower governor to performance: su -c 'cpupower frequency-set --governor performance' You need to do this every boot. You could create a systemd unit to do this for you along with any other real time settings you want to be set every boot. (Otherwise create a script and run it by hand.)<br></div>
<div>Install and run realTimeConfigQuickScan<br></div>
<div>su -c 'yum install realTimeConfigQuickScan'<br></div>
<div>Run /usr/bin/realTimeConfigQuickScan in a console and fix any issues it exposes. Run it again after you have fixed any issues to be sure.<br></div>
<div>Disable any services you do not require but be careful not to disable any important system services su -c 'yum install system-config-services' to monitor and manipulate services (Referred to as systemd units.)<br></div>
<div>Having looked into systemd quite deeply, systemd units which run from the timer targets can cause random xruns if they are not set to a low priority. Nice=19 IOSchedulingClass=idle IOSchedulingPriority=7 CPUSchedulingPolicy=idle is the kind of stuff I am trying out in systemd units that I have created and I have added to the timers target. Might be over kill. Completely disabling them and manually running them may be a better solution.<br></div>
<div>Consider turning off the wireless card on your laptop if it has one. They are notorious for causing xruns. Alternatively, set's the wireless card's driver irq to a priority just below your sound card driver in rtirq and also add it to the RTIRQ_NON_THREADED list.<br></div>
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<div>I don't have any experience of firewire interfaces but if you set the things mentioned above, you should hopefully achieve some level of success. Zero xruns is definitely possible.<br></div>
<div>Hope this helps.<br></div>
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<div>Kind Regards,<br></div>
<div>Tony<br></div>
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<div id="sig9724841"><div class="signature">--<br></div>
<div class="signature">Tony White<br></div>
<div class="signature"><a href="mailto:twhite@operamail.com">twhite@operamail.com</a><br></div>
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