Re: [PATCH v6 0/6] V4L2 Explicit Synchronization
From: Gustavo Padovan
Date: Thu Dec 21 2017 - 15:28:33 EST
2017-12-21 Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>:
> Em Mon, 11 Dec 2017 16:27:35 -0200
> Gustavo Padovan <gustavo@xxxxxxxxxxx> escreveu:
> > From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
> > Hi,
> > One more iteration of the explicit fences patches, please refer
> > to the previous version for more details about the general
> > mechanism
> > This version makes the patchset and the implementation much more
> > simple, to start we are not using a ordered capability anymore,
> > but instead we have a VIDIOC_ENUM_FMT flag to tell when the
> > queue in not ordered. Drivers with ordered queues/formats don't
> > need implement anything. See patches 1 and 2 for more details.
> > The implementation of in-fences and out-fences were condensed in
> > just patches 4 and 5, making it more self-contained and easy to
> > understand. See the patches for detailed changelog.
> > Please review! Thanks.
> Hi Gustavo,
> As I was afraid, the changes at the VB2 core makes it non-generic,
> breaking support for the DVB VB2 patchset. That's a branch with
> both patchsets applied:
> With the explicit fences patchset, the DVB streaming breaks:
> $ sudo perf stat dvbv5-zap -c ~/dvb_channel.conf "TV Brasilia RedeTV!" -o /dev/null -t120 -R
> Usando demux 'dvb0.demux0'
> lendo canais do arquivo '/home/mchehab/dvb_channel.conf'
> sintonizando em 557142857 Hz
> PID de vídeo 273
> dvb_set_pesfilter 273
> PID de áudio 274
> dvb_set_pesfilter 274
> Travado (0x1f) Sinal= -85,22dBm C/N= 18,57dB UCB= 8589933955 pós-BER= 0
> Travado (0x1f) Sinal= -85,24dBm C/N= 18,57dB UCB= 8589933955 pós-BER= 0
> Gravação iniciada para o arquivo '/dev/null'
> ERRO:DMX_REQBUFS failed: error=-1 (Invalid argument)
> ERRO:[stream_to_file] Failed to setup buffers!!! (Invalid argument)
> start streaming!!!
> copied 0 bytes (0 Kbytes/sec)
> Travado (0x1f) Sinal= -85,25dBm C/N= 18,57dB UCB= 8589933955 pós-BER= 0
I haven't tried it, not sure what could break it. I'll take a look on
> Performance counter stats for 'dvbv5-zap -c /home/mchehab/dvb_channel.conf TV Brasilia RedeTV! -o /dev/null -t120 -R':
> 7.001647 task-clock-msecs # 0.003 CPUs
> 251 context-switches # 0.036 M/sec
> 18 CPU-migrations # 0.003 M/sec
> 181 page-faults # 0.026 M/sec
> 17001058 cycles # 2428.151 M/sec
> 11342660 instructions # 0.667 IPC
> 349075 cache-references # 49.856 M/sec
> 70802 cache-misses # 10.112 M/sec
> 2.133343557 seconds time elapsed
> It also breaks support on V4L2, when fences is not used:
> $ ./contrib/test/v4l2grab
> (kernel crashes)
> I don't have a serial console on this machine to print what's
> wrong, but clearly there's something not right there :-)
2 days ago I fixed the a crash when not using fences: