Messages in this thread | | | Date | Wed, 21 Jun 2006 11:43:20 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: realtime-preempt for MIPS - compile problem with rwsem |
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On Wed, 21 Jun 2006, Ryan McAvoy wrote:
> > First, whenever sending mail about the -rt patch, always CC Ingo (and > > perhaps Thomas Gliexner and myself). > > Thanks, I will do that.
Ingo is the important one. Thomas and I are just the janitors Although Thomas is chief janitor :)
> > > 2.6.15 had lots of problems with -rt. Mainly the patch went through some > > major rework, and Ingo was busy getting mutexes into mainline. So the > > 2.6.15-rtX was sort of neglected. It would be best to use 2.6.16-rtX and > > maybe even 2.6.17-rtX > > > > Which also comes the question: Which -rt patch are you actually trying? > > patch-2.6.15-rt21 . I have also tried using the 2.6.16 kernel and
Hmm, 15-rt21 may have stabilized a bit. But I do still think the 16 series is much more stable.
> patch-2.6.16-rt29 and have the same problems with it. (I may be > constrained in having to use a 2.6.15 kernel ... but would be happy to > get 2.6.16 working /stable as a starting point.) > > > Yep, try the following patch: (completey untested since I don't have a > > mips machine). > > > > config RWSEM_GENERIC_SPINLOCK > > bool > > - depends on !PREEMPT_RT > > + depends on PREEMPT_RT > > default y > > I did just that when I first started with these patches and did > succeed in getting it compiling and booting. The resulting kernel, > however, is very unstable and hangs frequently with no output. (It > will hang within hours if left idle. I can hang it more quickly by > attempting to use it). I have deadlock detection turned on and have > confirmed that it does produce output at least for some deadlocks: > http://groups.google.com/group/linux.kernel/browse_frm/thread/1559667001b7da2d/2558b539a5adc660?lnk=st&q=realtime+preempt+mips&rnum=2&hl=en#2558b539a5adc660 > In the more common hangs though, I get no output.
That output looks like it had a deadlock on the serial output of sysrq key. But that back trace looks screwy.
> > I decided to review the changes I made in getting it to compile and > was hoping that this one may be the cause of the instability. I > thought that perhaps this change was incorrect because > include/asm-mips/rwsem.h is introduced by the rt-preempt patch and
Ha, you're right! (added John Cooper to this so he can clean up this mess ;)
> would only be used if RWSEM_GENERIC_SPINLOCK was off. [As well, it > seemed like something fundamental enough to account for the general > instability I am seeing.] >
Perhaps you can post all the changes you made as a patch to see if something else is wrong. It might also be best to see if you can get the latest working (2.6.17-rtX) and work your way backwards to the kernel version you really need.
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