What is the output of
lsof | grep frontend
when VDR is in the "idle" state?
On Sun, Oct 17, 2021 at 10:52:11PM +0300, Marko Mäkelä wrote:
> Tue, Oct 12, 2021 at 07:21:10PM +0300, glenvt18 wrote:
> > Here you can find an updated version of the patch:
> > https://github.com/glenvt18/vdr/commits/vdr-2.4.6
>
> Thank you. I just conducted some tests with my uncalibrated Agilent power
> supply. The USB cable of such low quality that the Raspberry Pi complained
> several times about undervoltage.
>
> I measured the following current draw at 5 volts, in ascending order:
>
> 81 mA: Raspberry Pi 2B shut down
> 200 mA: Raspberry Pi 2B powered up, no Ethernet plugged in
> 240 mA: Ethernet cable plugged in (HDMI cable makes no difference)
> 320 mA: Ethernet + USB DVB stick plugged in
> 440 mA: compiling VDR with "make -j4" (all CPU cores busy)
> 550 mA: VDR playing back a recording
> 530 mA: recording paused in VDR
> 510 mA: EPG scan running
> 600 mA: VDR displaying live DVB-T2
>
> https://github.com/glenvt18/vdr/commit/b368f67d00d0b466ae36028efb9336e81f77dba8
> applied cleanly on the latest VDR source. I changed the PowerdownTimeoutM
> from 15 to 1 minute to speed up my testing.
>
> The patch only had a minimal impact. After 1 or 2 minutes of the playback of
> a recording being paused, the power consumption dropped from 530 mA to 500
> mA.
>
> I noticed that VDR is consuming about 5% of the CPU power according to
> "top". Could it not be made more event-based? It might be interesting to
> check with "powertop" how many wakeups per second there are, and with "perf
> record" and "perf replay" (or simply "perf top") where the CPU cycles are
> being spent when the playback of a recording is paused.
>
> The bulk of the the power consumption ought to be caused by the USB DVB
> stick not being in fully idle state. After all, utilizing all 4 CPU cores
> during the "make -j4" minutes showed a pretty stable power consumption of
> 440 mA for several minutes, which is much less than when the VDR process was
> running.
>
> Here is a summary of the power consumption measured at 5 volts.
>
> 1.2 W (240 mA) mostly idle Raspberry Pi 2B (Ethernet plugged in)
> 1.6 W (320 mA) USB DVB stick plugged in, VDR not running
> 2.5 W (500 mA) lowest power consumption achieved with VDR
> 3.0 W (600 mA) VDR displaying live TV
>
> My conclusion is that I will configure udev so that VDR will automatically
> start up or shut down when the USB stick is plugged in or removed. In that
> way, the power consumption of the system will only be more than doubled when
> VDR is actually in use.
>
> I am planning to install the most recent Raspberry Pi and to document the
> minimal changes on top of that.
>
> Best regards,
>
> Marko
>
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--
glenvt18
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