<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - Issue of CPU usage with HiFiBerry driver snd_soc_hifiberry_amp with Debian Wheezy kernel 3.12.28" href="https://bugs.freedesktop.org/show_bug.cgi?id=84585#c11">Comment # 11</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - Issue of CPU usage with HiFiBerry driver snd_soc_hifiberry_amp with Debian Wheezy kernel 3.12.28" href="https://bugs.freedesktop.org/show_bug.cgi?id=84585">bug 84585</a> from <a class="email" href="mailto:alessandroferri_015@fastwebnet.it" title="Alessandro Ferri <alessandroferri_015@fastwebnet.it>"> Alessandro Ferri</a> <pre>About the frequency of the CPU, I have checked the parameters of current, max and min cpu freq, these are the results: pi@raspberrypi ~ $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq 700000 pi@raspberrypi ~ $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq 700000 pi@raspberrypi ~ $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq 700000 I have also tried to change the configuration parameters of the CPU /boot/config.txt, in this manner: # Meaningful word.. This means 'enable cpu freq scaling' force_turbo=0 # Set lowest cpu freq. By default, it's 700. arm_freq_min=700 or #uncomment to overclock the arm. 700 MHz is the default. arm_freq=800 # for more options see <a href="http://elinux.org/RPi_config.txt">http://elinux.org/RPi_config.txt</a> # Meaningful word.. This means 'enable cpu freq scaling' force_turbo=0 # Set lowest cpu freq. By default, it's 700. arm_freq_min=800 with these results: pi@raspberrypi ~ $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq 700000 pi@raspberrypi ~ $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq 800000 pi@raspberrypi ~ $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq 700000 but the problem of the excessive use of cpu by pulseaudio remains and persists. I do not think it is due to a low cpu speed setting. (In reply to Tanu Kaskinen from <a href="show_bug.cgi?id=84585#c8">comment #8</a>) > One important difference is that the configured sink latency is much lower > with 3.12.25 than with 3.12.28. I don't know how the kernel could affect > that, though, except by varying the maximum sink buffer size, but in this > case it seems that with both kernels the sink buffer size is the same. > > The configured sink latency is determined by what applications request. In > this case there are shairport and LightSone connected to the sink (LightSone > is actually connected to the monitor source of the sink, but if LightSone > requests low latency from the source, that request will propagate to the > monitored sink also). If shairport or LightSone have different latency > configuration between the kernels, that would explain the difference in the > configured sink latency. (The configured latency of the monitor source is > the same in both cases, though, which suggests that LightSone is not to > blame here). To get information about what latencies the applications > request, you could attach (as an attachment, not in the comment!) the > verbose log of pulseaudio in both cases. See > <a href="https://wiki.ubuntu.com/PulseAudio/Log">https://wiki.ubuntu.com/PulseAudio/Log</a> for instructions. > > It's unexpected that lower latency leads to lower cpu use. Is it possible > that the cpu runs at a lower speed with 3.12.28, causing higher figures in > top? Here is some information about cpu speed scaling on Raspberry Pi: > <a href="http://with-raspberrypi.blogspot.com/2014/03/cpu-frequency.html">http://with-raspberrypi.blogspot.com/2014/03/cpu-frequency.html</a></pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>