* Peter Maydell (peter.mayd...@linaro.org) wrote: > On Tue, 26 Feb 2019 at 12:30, Peter Maydell <peter.mayd...@linaro.org> wrote: > > > > On Tue, 26 Feb 2019 at 12:17, Dr. David Alan Gilbert > > <dgilb...@redhat.com> wrote: > > > > > > * Peter Maydell (peter.mayd...@linaro.org) wrote: > > > > Backtrace of process 125450: > > > > Thread 6 (Thread 0xfff800012de0b900 (LWP 127434)): > > > > #0 0xfff80001034c5cdc in futex_abstimed_wait_cancelable (private=0, > > > > abstime=0xfff800012de09f88, expected=0, futex_word=0x10001236574) > > > > at ../sysdeps/unix/sysv/linux/futex-internal.h:205 > > > > #1 0xfff80001034c5cdc in do_futex_wait (sem=0x3c, > > > > abstime=0xfff800012de09f88) at sem_waitcommon.c:111 > > > > #2 0xfff80001034c5e00 in __new_sem_wait_slow (sem=0x10001236570, > > > > abstime=0xfff800012de09f88) at sem_waitcommon.c:181 > > > > #3 0x000001000091dacc in qemu_sem_timedwait (sem=0x10001236570, > > > > ms=<optimized out>) at /home/pm215/qemu/util/qemu-thread-posix.c:289 > > > > #4 0x000001000078ae28 in migration_thread (opaque=0x100012364a0) at > > > > /home/pm215/qemu/migration/migration.c:3125 > > > > > > So migration is still apparently running, it's rate-limiting > > > using a timedwait; but 'ms' has been unhelpfully optimised out; could > > > it be stuck in here for some reason? > > > > I looked at this from frame 4, and ms is 64. On the other > > hand if I tell gdb to 'fin' it doesn't ever leave > > futex_abstimed_wait_cancelable(), so I wonder if we're > > managing to get the conversion of the relative time into > > an absolute deadline wrong somehow ?? > > Very weirdly, gdb shows me an absolute timestamp passed > to the futex function which is indeed in the past, so it > seems like the issue is that the kernel isn't returning > control to us when the timestamp expires for some reason.
I wonder if we have any more luck with blacklisting CONFIG_SEM_TIMEDWAIT - I wonder if it uses a different kernel call? Dave > thanks > -- PMM -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
