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Re: [Qemu-devel] What is the best commit for record-replay?
From: |
Pavel Dovgalyuk |
Subject: |
Re: [Qemu-devel] What is the best commit for record-replay? |
Date: |
Wed, 20 Sep 2017 09:17:41 +0300 |
> From: Alex Bennée [mailto:address@hidden
> >
> >>>
> >>>> >
> >>>> > Hope you've already found the solution (as the last post was on 2 May)
> >>>> > and it's just got missed the mailing list.
> >>>
> >>> As I know, RR is still broken in the current version.
> >>> It was caused by the MTTCG implementation.
> >>> Alex Bennee tried to fix RR back. Alex, have you found any solution?
> >>>
> >>> We also trying to find a way to fix RR. It seems, that we will reinvent
> >>> BQL for RR.
> >>
> >> I think the method outlined in my RFC is the way to go, essentially the
> >> RR mutex taking over for the what the BQL did. The RFC patch hadn't
> >> hoisted the mutex for the additional devices so I'm just re-basing now
> >> and I'll see if I can make the changes for Igor's test case.
> >>
> >> --
> >> Alex Bennée
>
> Could you try:
>
> https://github.com/stsquad/qemu/tree/bql-and-replay-locks-v2
>
> And report back?
Most of the code look reasonable.
Isn't better to lock before acting with icount in the following function?
static void prepare_icount_for_run(CPUState *cpu)
{
if (use_icount) {
int insns_left;
/* These should always be cleared by process_icount_data after
* each vCPU execution. However u16.high can be raised
* asynchronously by cpu_exit/cpu_interrupt/tcg_handle_interrupt
*/
g_assert(cpu->icount_decr.u16.low == 0);
g_assert(cpu->icount_extra == 0);
cpu->icount_budget = tcg_get_icount_limit();
insns_left = MIN(0xffff, cpu->icount_budget);
cpu->icount_decr.u16.low = insns_left;
cpu->icount_extra = cpu->icount_budget - insns_left;
if (replay_mode != REPLAY_MODE_NONE) {
replay_mutex_lock();
}
}
}
Pavel Dovgalyuk