Re: [Xenomai] Hung task on Xenomai patched ARM 3.8.13 BeagleBone Kernel

[Charles Steinkuehler <charles@steinkuehler.net>]

On 10/16/2013 5:44 AM, Gilles Chanteperdrix wrote:
> It points to several possible problems. So, a question, do you get this
> while a Xenomai task is running? Or on an otherwise idle system?
> Second question: is the Linux timer system running correctly, for
> instance does "sleep 10" sleeps a little bit before returning, or does
> it fail to return too?

In the test case, the system is otherwise idle when this happens.  It is
the large amount of "disk" I/O to the SD card that causes the mmcqd
process to hang.  Also, the grep -r doesn't fail immediately.  It runs
for a while, sometimes getting far enough it finds one or two of the
four matching files in /usr, then the mmcqd task hangs.

Other than this occasional glitch, the kernel and system work normally.
 This is the same kernel I am using to run LinuxCNC and I've managed to
get through many overnight 8+ hour prints, and have had uptimes of
several weeks.

I suspect an occasional lost interrupt or maybe a race condition or
something specific to the AM335x MMC driver.  Xenomai seems otherwise to
run perfectly well on this hardware.

Note that think I have been seeing this issue occasionally for as long
as I have been testing Xenomain on the BeagleBone.  I mostly chalked it
up to a bad SD card I had, but it seems like there's a deeper issue
involved.  What changed is I just recently got a report with the very
simple way to trigger the bug using the recursive grep.

-- 
Charles Steinkuehler
charles@steinkuehler.net

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 261 bytes
Desc: OpenPGP digital signature
URL: <http://www.xenomai.org/pipermail/xenomai/attachments/20131016/6546b01f/attachment.pgp>