Stability issues with XBian (sporadic hangs)

[Rilhas]

(22nd Sep, 2013 09:12 AM)mk01 Wrote:  nothing like to be 100% sure, but you got my attention with the USB traffic / utilization.

there seems to be few issues with the RPIs usb design causing problems starting from usb devices not found to problems with IRQ/timings ending with kernel panics - related to some usage pattern / usb devices combinations.

FIQ split should be a help there, now by default turned on with 3.10.y kernels. this wasn't the case with older branches (or months ago). XBian B1 / 1.1 wasn't using those patches - but Raspbian does use them / has patched kernels.

nevertheless it is my assumption, not proof of something, but generally speaking there are not much other relevant differences, if any.

for example there was an issue opened at github recently https://github.com/xbianonpi/xbian/issues/457 which would make it (together with you and one other) three 'reported' cases with similar symptoms I know of.

I will just tell you the same as in the comment to the issue - Beta1 branch will retire very soon. If you have reasons to go for XBMC bundled distro like XBian or RaspBMC (I have the feeling it won't be OpenELEC), give it a week or two until Beta2 is released and give it a try then.

Your post makes sense to me on so many levels, while at the same time gets me confused about a few situations I encountered.

I started suspecting USB problems when I tried to get a composite video capture card to work with Raspbian. The capture device was not recognized in Raspbian, and various posts in various forums commented on the USB issues with the Pi and also of support being better in 3.7+ kernels.

My Raspbian is 3.6, and because XBian was 3.9 I expected it to be better at the USB issues, but the capture cards still didn't work. In fact (and that is where the first contradiction showed up), it seemed a lot worse with the capture cards I tried (detection problems, hanging, intermittent registrations and deregistrations of /dev/video0). Still, I tested about 4 capture cards on 2 different Pi's with both Raspbian and XBian, plus one of the power supplies I used turned out to be faulty, and sometimes with a USB hub and sometimes without. So I gave up trying to make sense of it all, and gave up capture cards for a while.

Then, yesterday, after the 8 or 10 days of running Raspbian and my "media center" without problems (as I mentioned in a previous post) I decided to try the capture cards in Raspbian again. I apt-updated and then apt-upgraded, and it all seemed somewhat better with the cards, but they still didn't work.

I gave up the video capture again, disconnected all the capture cards, rebooted, but - and this is where I was blown away - after a few hours the Pi hung. I turned on the TV looking for panics, but when my Pi is rebooted with HDMI matrix using another HDMI source the result is that the Pi's console is all black and no text is displayed. Since I had rebooted the Pi in these conditions the TV showed nothing, so there might be a panic that I was not able to see (only later did I think that I could have tried the composite output before restarting the Pi, but by then it was too late, I'll remember it next time).

What came to my mind right away was that the unupdated/unupgraded Raspbian (originally from NOOBS v1.2.1, I think) might have been more tolerant to the Pi's USB instabilities than both the updated/upgraded Raspbian and XBian (which is a few versions ahead of Raspbian). Maybe some change in versions after that "original" Raspbian introduced something that is affected by my setup, while previously it wasn't.

Corroborating this, after the Raspbian update/upgrade I immediately noticed something was worse, because the lights in the hallway took longer to turn on than they did before (these specific lights exchange a lot of messages with the server, so they are a noticeable and clear indicator that something changed). The FTDI USB driver in the Pi has always been the domotics bottleneck, and has always governed the reaction time of sensors and actuators, so the fact that it is now slower (2 seconds to turn on instead of the 0.2 to 0.3 seconds it took before) makes me suspect of a degradation in USB performance in the updated/upgraded version of Raspbian.

... coincidentally, turning on the lights in XBian was also slow (maybe the same 2 seconds), but I have always attributed that to the high CPU consumption of XBMC, even while sitting idle, coupled with is niceness of -3. Now I'm beginning to think that the delay in XBian was not CPU related, but USB related instead, and the theory that the new kernels are the ones causing me problems makes even more sense.

Although this theory made complete sense to me yesterday, it doesn't hold when confronted with your explanation that Raspbian had used patches and that XBian hadn't, because when updating/upgrading Raspbian the behaviour becomes closer to that of XBian (unless in case of some weird possibilities, like the updated/upgraded Raspbian not using the patches anymore).

This is all very recent, so I will still need the Pi to hang a few more times to draw any conclusions

As for the next XBian release - I'll be looking forward to it and will surely give it a try when it comes out.