On Aug 23, 2013, at 1:53 PM, Phil Mayers wrote: > On 08/23/2013 06:39 PM, Lucas Taylor wrote: > >> I suppose the obvious answer may be that the Pi is underpowered for >> this task, but I am hoping to better understand why. I may be able >> to defer logging to a queue or find other workarounds, but I'd like >> to figure out why basic usage of logging could be causing this. Any >> thoughts as to what I could be looking at next would be appreciated. > > What is the data rate, and the nature of the serial ports (e.g. UART or USB?) > > Your suggestion of CPU rings a little bell for me; IIRC the Pi had some > (ahem) sub-optimal behaviour w.r.t. the USB controller in some hardware > versions. There was some mild controversy over this, with various accusations > slung back and forth in the forums, people getting banned for "continuing to > talk about it" and so on. But I seem to recall timely data delivery under CPU > load was a symptom, and it might be the overhead of Twisted/Python/logging > drives the Pi too hard. > > Where is the logging directed - I'm assuming NV storage which is the SD card? > - you might try logging to RAM and not touching the storage or bus. >
9600bps, using USB-Serial adapters (tried 3 different supported chipsets). Logging to local storage and also to stdout. Now that I have waded through many Pi forum posts about USB behavior trying to figure this out, it seems that most of the USB-Serial issues had to do with freezes when accessing the serial port, or hanging after some length of continuous use. Those issues appear to have been resolved (or at least I am not experiencing them), but it does seem there may still be lingering hardware issues in search of driver fixes according to the forums. Lots of folks are using the Pi w/ USB serial adapters to good effect, though, so who knows? At any rate, I don't think there is much to be done on the Twisted side. I have a few minor things left to try, but I have a feeling my curiosity about the root cause of this is going to disappear in favor of ponying up for a more substantial piece of hardware... Thanks for your reply, Lucas _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
