On 2018-07-18 12:28:48 [+0200], Mike Galbraith wrote: > > Okay, so you did not test this because you can't compile. > > Nope, the running kernel, the one that is doing the segfaulting etc, > has the patches applied. > > It is exhibiting that symptom because those patches do not cure this > symptom, one which I verified to be present in virgin 4.14-rt as well. > The pseudo-patch I sent, disabling preemption where it is assumed to be > disabled instead, does cure it. With preemption so disabled, I can > beat on affected kernels (>=4.14-rt) as long as I like.
ah. so gcc shows the problem instead gcc explodes with the patch applied. Okay. Let me stare at this a little more… > This particular 48 core Cavium is very slow, maybe that makes it easier > to reproduce, dunno. According to pipe-test, the thing is essentially > a dozen RPi super-glued together. pipe-test pinned to a single core > can only context switch at ~40KHz with PREEMPT_RT, or ~90 with > NOPREEMPT, comparable to measurement done in real deal RPi. > > -Mike Sebastian
