Hi,
same phenomenon here. Thinkpad X201 with i7 (620LM) processor consumes
~ 6.5 Watt when idle. When playing audio the power consumption increases
above 13 Watt, no matter if playing via pulseausio or direct alsa. In
addition the cpu temperature raises from 48° to 56°.
Using turbostat from package linux-tools-common shows that the package
c-states change.
output from tubostat when idle, no audio:
cr CPU %c0 GHz TSC %c1 %c3 %c6 %pc3 %pc6
0.82 1.38 1.99 1.31 2.76 95.12 4.02 91.83
0 0 1.26 1.38 1.99 0.83 2.33 95.58 4.02 91.83
0 1 0.32 1.38 1.99 1.78 2.33 95.58 4.02 91.83
2 2 0.84 1.38 1.99 1.32 3.19 94.66 4.02 91.83
2 3 0.86 1.36 1.99 1.30 3.19 94.66 4.02 91.83
output when playing audio:
cr CPU %c0 GHz TSC %c1 %c3 %c6 %pc3 %pc6
2.52 1.21 1.99 4.55 19.16 73.77 0.00 0.00
0 0 4.26 1.21 2.00 4.76 14.55 76.42 0.00 0.00
0 1 2.70 1.21 1.99 6.33 14.55 76.42 0.00 0.00
2 2 2.19 1.21 1.99 2.91 23.77 71.13 0.00 0.00
2 3 0.93 1.21 1.99 4.17 23.77 71.13 0.00 0.00
"position_fix=1" as parameter to snd-hda-intel seems to save about 0.5-1 Watt,
but even with that audio still consumes far too much power. +6 Watt means half
running time when on battery.
Since the combination of i5/i7 processors of the first generation and
the conexant audio codec cx20585 can be found in other notebooks too
(e.g. Thinkpad T410, T510, and other brands for sure) I would suppose
that other people should be affected too.
So far I have tested several releases of Ubuntu and openSUSE, both i386
and x86_64, with distribution and vanilla kernels, the problem shows up
everywhere.
Please let me know which additional information is needed to localize
the source of this problem.
Ralf
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https://bugs.launchpad.net/bugs/1065942
Title:
playing audio prevent cpu from entering c states
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