The role of the DPF is to trap the carbon soot the engine throws out on the combustion cycle and also to clean out the diesel exhaust smell. Thats what makes this engine "smoke free" - my mercedes E300D here also has it - and it did get choked to the point of the engine run failure - meaning it refused to start unless the exhaust was unbolted from the head.
The DPF traps carbon soot and deposits it on its ceramic honeycomb, and can only be burned off by heating it up, This is accomplished by the engine pushing a little more fuel into the engine to generate excess heat which sets off the fiery heat and the DPF cleans itself. To do this get on to a highway in a lower gear to speed up the engine and bury the pedal to clean out the DPF. It will clean itself out. - Infact your dashboard would have a symbol or gauge to show you its breathing capacity.
My mercedes' DPF (cat) got blocked because the previous owner never accelerated beyond 2800 rpm and the EGR was kind of sticky too. And this engine is the simplest - meaning no ECU, no electronic wizardry, even the pump is shut off by vacuum. The remedy for this car is to run it to redline (5500 rpm) every two weeks on the highway over a hill for the DPF to clean out itself.
I could get rid of it as TX has no emmissions laws for diesels but I didnt as I did not want my car to sound like a Honda civic with a cheap farting muffler.