I went to LKML for context, so I return with context.
When 3.8-rc1 was released, “Rafael J. Wysocki” reported 100% CPU usage by knotify4(part of KDE) on OpenSUSE Thubleweed with pulseaudio as audio server.
At which Mauro Carvalho Chehab replies starting with blaming pulseaudio(why? Srsly, why? I don’t like it, but this is just troll behaviour) and saying pulseaudio(which is NOT knotify4) should not try to use V4L2.