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oss:jackfreqd:start [13.12.2010 00:05] rgareus created |
oss:jackfreqd:start [28.02.2020 13:56] (current) rgareus |
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| ====== jackfreqd ====== | ====== jackfreqd ====== | ||
| - | Inspired by discussion with Fernando Lopez-Lezcano on [[http://lists.linuxaudio.org/pipermail/linux-audio-user/2010-December/074539.html|LAU]] and [[http://permalink.gmane.org/gmane.comp.audio.jackit/22839|jack-dev]]. I became motivated to create a tool that changes CPU frequency according to DSP load to address the issue on multi-core systems where system-load may still be too low for a default CPU governor to react while DSP load is already at the limit, causing x-runs. | + | Inspired by discussion with Fernando Lopez-Lezcano on [[http://lists.linuxaudio.org/pipermail/linux-audio-user/2010-December/074539.html|LAU]] and [[http://permalink.gmane.org/gmane.comp.audio.jackit/22839|jack-dev]]. I became motivated to create a tool that changes the CPU frequency according to DSP-load in order to address an issue on multi-core systems where system-load may still be too low for a default CPU governor to react while DSP load is already at the limit, causing x-runs. |
| - | ''jackfreqd'' is heavily based on [[http://www.deater.net/john/powernowd.html|powernowd]]. Instead of taking CPU load as parameter for deciding on CPU frequency it uses [[http://jackaudio.org|JACK]] DSP load and it only supports the powernowd's //aggressive// mode ((Aggressive more changes frequency by a sawtooth function. The system immediately jumps to the highest frequency whenever usage exceeds a given threshold (//high-water-mark//), and decreases by "step" Hz as usage drops below a //low-water-mark//)). Optionally ''jackfreqd'' can also take CPU load into account, which comes in handy when the JACK-daemon is temporarily unavailable or if frequency scaling should also be based on non-audio processes. | + | ''jackfreqd'' is heavily based on [[http://www.deater.net/john/powernowd.html|powernowd]]. Instead of taking CPU load as parameter for deciding on the CPU frequency ''jackfreqd'' uses [[http://jackaudio.org|JACK]] DSP-load and ''jackfreqd'' only supports the powernowd's //aggressive// mode ((Aggressive mode changes frequency by a sawtooth function. The system immediately jumps to the highest frequency whenever usage exceeds a given threshold (//high-water-mark//), and decreases by "step" Hz as usage drops below a //low-water-mark//)). Optionally ''jackfreqd'' can also take CPU load into account which comes in handy when the JACK-daemon is temporarily unavailable or if frequency-scaling should also be done for on non-audio processes. |
| In order to gain access to modify CPU-speed and do so quickly, ''jackfreqd'' needs to be run as //root//. ''jackfreqd'' includes support to assume a given user-id which runs the JACK-daemon, and also to auto-detect a running JACK instances and (re) connect to it. | In order to gain access to modify CPU-speed and do so quickly, ''jackfreqd'' needs to be run as //root//. ''jackfreqd'' includes support to assume a given user-id which runs the JACK-daemon, and also to auto-detect a running JACK instances and (re) connect to it. | ||
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| ===== Source ===== | ===== Source ===== | ||
| - | * [[http://rg42.org/gitweb/?p=jackfreqd.git|Repository, Changelog]] | + | In Feb 2020 Oleg Samarin has taken over maintenance. The repo was moved to github, please update your URL: |
| - | * %%git://rg42.org/jackfreqd%% | + | |
| - | * [[http://rg42.org/gitweb/?p=jackfreqd.git;a=snapshot;sf=tgz|snapshot]], [[http://rg42.org/gitweb/?p=jackfreqd.git;a=snapshot;h=debian;sf=tgz|debianized source]] | + | |
| - | ===== Installation ===== | + | * <del>[[http://rg42.org/gitweb/?p=jackfreqd.git|Repository, Changelog]]</del> |
| + | * https://github.com/oleg68/jackfreqd | ||
| - | Stop or remove existing CPU frequency scaling daemons from the system. | + | ''jackfreqd'' can be distributed in terms of the [[http://www.gnu.org/licenses/gpl2.html|GNU General Public License]]. |
| - | git clone git://rg42.org/jackfreqd | + | ===== Usage ===== |
| - | cd jackfreqd | + | |
| - | make | + | |
| - | sudo make install | + | |
| - | sudo /etc/init.d/jackfreqd start | + | |
| - | To launch it on bootup you need to create symlinks in ''/etc/rc?.d/''. e.g by running ''update-rc.d jackfreqd defaults''. | + | Consult the man page ''man jackfreqd'' or run ''jackfreqd -h'' for details. |
| - | On debian you can automate that: | + | Note that, while CPU frequency scaling is usually not a problem with JACK, Front-Side-Bus frequency scaling and PCI power-saving often causes x-runs with JACK. The latter can usually be disabled in the BIOS. |
| - | git clone git://rg42.org/jackfreqd | + | |
| - | cd jackfreqd | + | |
| - | git checkout -b debian origin/debian | + | |
| - | git-buildpackage --git-upstream-branch=master --git-debian-branch=debian -rfakeroot | + | |
| - | sudo dpkg -i ../jackfreqd_*.deb | + | |
| - | + | ||
| - | ===== Usage ===== | + | |
| - | + | ||
| - | Consult the man page ''man jackfreqd'' or run ''jackfreqd --help'' for details. | + | |
| ===== Discussion with Fernando ===== | ===== Discussion with Fernando ===== | ||
| - | + | >>> //Fernando:// | |
| - | >> To reproduce the issue you need to be quite "tuned" (in the wrong way), | + | >>> To reproduce the issue you need to be quite "tuned" (in the wrong way), |
| - | >> you need an application that uses two cores at about 50-60% and then you | + | >>> you need an application that uses two cores at about 50-60% and then you |
| - | >> change the connections so that they have to execute in series in jackd. | + | >>> change the connections so that they have to execute in series in jackd. |
| - | >> Before the connection change everything is fine as they execute in | + | >>> Before the connection change everything is fine as they execute in |
| - | >> parallel. After the connection no cores trigger the cpuspeed scaling but | + | >>> parallel. After the connection no cores trigger the cpuspeed scaling but |
| - | >> jackd misses the deadline anyway... In my case it was even worse, when I | + | >>> jackd misses the deadline anyway... In my case it was even worse, when I |
| - | >> set the speed to "high" it would almost work - doing other things would | + | >>> set the speed to "high" it would almost work - doing other things would |
| - | >> trigger xruns and then to cap it off stopping cpuspeed would push things | + | >>> trigger xruns and then to cap it off stopping cpuspeed would push things |
| - | >> over the edge and I would get no xruns. Bad luck in a way... | + | >>> over the edge and I would get no xruns. Bad luck in a way... |
| - | >> | + | >>> |
| - | > | + | >> //Robin:// |
| - | > yes, there is a short delay when the CPU switches speeds, but it should | + | >> yes, there is a short delay when the CPU switches speeds, but it should |
| - | > be irrelevant. I intent 'jackfreqd' to do the same as you do: switch to | + | >> be irrelevant. I intent 'jackfreqd' to do the same as you do: switch to |
| - | > "high CPU performance" when starting serious audio work and go back to | + | >> "high CPU performance" when starting serious audio work and go back to |
| - | > low-power only at the end of the session. | + | >> low-power only at the end of the session. |
| - | > | + | >> |
| - | > It uses very small High- and Low-watermarks: as soon as the DSP load | + | >> It uses very small High- and Low-watermarks: as soon as the DSP load |
| - | > goes above 50% : CPU freq switches to 100%. | + | >> goes above 50% : CPU freq switches to 100%. |
| - | > If and only if DSP load drops below 10% the CPU-speed is reduced by | + | >> If and only if DSP load drops below 10% the CPU-speed is reduced by |
| - | > one-step again. | + | >> one-step again. |
| - | > | + | >> |
| - | > There can be a x-run at the start of the session: If you manage to go | + | >> There can be a x-run at the start of the session: If you manage to go |
| - | > from <50% to >100% DSP load in one step.. (since 0.0.2 jackfreq checks | + | >> from <50% to >100% DSP load in one step.. (since 0.0.2 jackfreq checks |
| - | > DSP load periodically and on each JACK graph change. The algorithm can | + | >> DSP load periodically and on each JACK graph change. The algorithm can |
| - | > be optimized: lower the periodic update period after each graph-change | + | >> be optimized: lower the periodic update period after each graph-change |
| - | > for a few cycles..). I still need to play around to find good defaults | + | >> for a few cycles..). I still need to play around to find good defaults |
| - | > for the high/low watermarks, etc.. For the time being I'm aiming at a | + | >> for the high/low watermarks, etc.. For the time being I'm aiming at a |
| - | > proof-of-concept. | + | >> proof-of-concept. |
| - | > | + | >> |
| + | > //Fernando:// | ||
| + | >Sounds like a good solution and strategy and it would be very useful to have... | ||
| {{tag>audio development floss jack}} | {{tag>audio development floss jack}} | ||