[PlanetCCRMA] Fedora 20 3.12.12-300.rt19.1 with Focusrite Saffire Pro40
Donald Steven
t6sn7gt at aim.com
Thu Aug 28 04:29:33 PDT 2014
Thanks Tony. This is great!
Best,
Don
On 08/23/2014 11:56 AM, Tony White wrote:
> Hi Don,
> You should use 48000 sample rate. It is jack's default rate, the
> recording studio standard and the most tested.
> 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.
>
> Preempt (low latency)... False
> 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.
> 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.
> Be sure to add the threadirqs kernel parameter to the kernel-rt boot
> entry option in grub.cfg.
> Install the package rtirq and enable it with: su -c 'yum install rtirq
> && sytemctl enable rtirq'
> 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.
> http://subversion.ffado.org/wiki/IrqPriorities
> 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.)
> Install and run realTimeConfigQuickScan
> su -c 'yum install realTimeConfigQuickScan'
> 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.
> 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.)
> 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.
> 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.
> 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.
> Hope this helps.
> Kind Regards,
> Tony
> --
> Tony White
> twhite at operamail.com <mailto:twhite at operamail.com>
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