DragonFly kernel List (threaded) for 2008-04
DragonFly BSD
DragonFly kernel List (threaded) for 2008-04
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Re: ugen(4) and poll(2)


From: "Simon 'corecode' Schubert" <corecode@xxxxxxxxxxxx>
Date: Fri, 25 Apr 2008 01:51:13 +0200

Hasso Tepper wrote:
As far as I can see what happens is that daemon opens ugen(4) device correctly and starts to poll(2) interrupt endpoint of the device (devices have single interface). The trouble is that poll(2) seems to ignore timeout. It doesn't return until there is data available in the descriptor. Ie I can make poll(2) to return with poking device, but till then it blocks.

Before I dig deep into areas I'm not familiar with ... Any ideas why and where it might happen? Anyone seen something like this?

In which waitchan is the process? If it is in "poll" and you're really passing a proper timeout value, then everything should work as advertised. Does a ktrace show only the poll and no return? Sometimes processes tend to re-call poll over and over again (maybe due to an interrupting signal).


cheers
  simon

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