[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC PATCH v1 0/9] MTTCG and record/replay fixes for rc
Re: [Qemu-devel] [RFC PATCH v1 0/9] MTTCG and record/replay fixes for rc3
Tue, 04 Apr 2017 09:50:16 +0100
mu4e 0.9.19; emacs 25.2.13
Paolo Bonzini <address@hidden> writes:
> On 03/04/2017 14:45, Alex Bennée wrote:
>> cpus: check cpu->running in cpu_get_icount_raw()
>> I'm not sure the race happens and once outside of cpu->running the
>> icount counters should be zero. However it seems a sensible
> Yeah, I think this is unnecessary with patch 7's new assertions.
I can drop the patch.
>> I think the cpus: patches should probably go into the next
>> pull-request while we see if we can come up with a better final
>> solution for fixing record/replay. However given how long this
>> regression has run during the release candidate process I wanted to
>> update everyone on the current status and get feedback ASAP.
> I agree. I'm not sure exactly how the final race happens, but if it
> causes divergence it would be caught later by the record/replay
> mechanism, I think.
It's odd because everything should be sequenced by the BQL. The
main-loop holds the BQL while writing out checkpoints and everything
that can trigger output to the replay stream should be under BQL as
- VIRTUAL timers in the outer loop
- MMIO triggered events (block, char, audio)
- Interrupt processing
In fact I wonder if replay_mutex could just be dropped and the BQL used
to protect all of this stuff.
I'll have to experiment with some asserts to see if this is every not
[Qemu-devel] [RFC PATCH v1 9/9] replay: gracefully handle backward time events, Alex Bennée, 2017/04/03
[Qemu-devel] [RFC PATCH v1 4/9] target/i386/misc_helper: wrap BQL around another IRQ generator, Alex Bennée, 2017/04/03
[Qemu-devel] [RFC PATCH v1 3/9] scripts/replay-dump.py: replay log dumper, Alex Bennée, 2017/04/03
Re: [Qemu-devel] [RFC PATCH v1 0/9] MTTCG and record/replay fixes for rc3, Paolo Bonzini, 2017/04/03
- Re: [Qemu-devel] [RFC PATCH v1 0/9] MTTCG and record/replay fixes for rc3,
Alex Bennée <=