[mythtv] RetuneMonitor generates significant load with DVB cards without hardware i2c support
janne-mythtv at grunau.be
Tue Jul 25 22:13:53 UTC 2006
The cause is the FE_READ_STATUS ioctl in RetuneMonitor. It blocks for
approximately 10ms on cards with a cx88 or bt8xx pci bridge and the
pluto2 device. These devices have no hardware i2c support. For the cx88
it's just not implemented yet. They use i2c bit banging instead.
This wouldn't be a problem if the signalmonitor is only for tuning
checks before channel changes. But it isn't that good for the active
I see two options to reduce the load:
1. don't call RetuneMonitor that often, 2-3 times per second is probably
enough. This may slowdown tuning for rotors.
2. disable the RetuneMonitor after IsAllGood() is true. This removes the
functionality but if I understand it correctly the main feature of the
RetuneMonitor is to make tuning more reliable with rotors and
diseq-switches. Currently the eitscanner is more reliable than
live-tv/recordings since it has a continous LOCK check.
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