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Re: [Qemu-devel] [PATCH v2 12/12] replay: assert time only goes forward
From: |
Pavel Dovgalyuk |
Subject: |
Re: [Qemu-devel] [PATCH v2 12/12] replay: assert time only goes forward |
Date: |
Wed, 5 Apr 2017 16:33:32 +0300 |
> From: Alex Bennée [mailto:address@hidden
>
> If we find ourselves trying to add an event to the log where time has
> gone backwards it is because a vCPU event has occurred and the
> main-loop is not yet aware of time moving forward. This should not
> happen and if it does its better to fail early than generate a log
> that will have weird behaviour.
>
> Signed-off-by: Alex Bennée <address@hidden>
> ---
> replay/replay-internal.c | 4 ++++
> replay/replay.c | 4 ++++
> 2 files changed, 8 insertions(+)
>
> diff --git a/replay/replay-internal.c b/replay/replay-internal.c
> index bea7b4aa6b..fca8514012 100644
> --- a/replay/replay-internal.c
> +++ b/replay/replay-internal.c
> @@ -195,6 +195,10 @@ void replay_save_instructions(void)
> if (replay_file && replay_mode == REPLAY_MODE_RECORD) {
> replay_mutex_lock();
> int diff = (int)(replay_get_current_step() -
> replay_state.current_step);
> +
> + /* Time can only go forward */
> + assert(diff >= 0);
> +
> if (diff > 0) {
This "if" is useless then.
> replay_put_event(EVENT_INSTRUCTION);
> replay_put_dword(diff);
> diff --git a/replay/replay.c b/replay/replay.c
> index 9e0724e756..f810628cac 100644
> --- a/replay/replay.c
> +++ b/replay/replay.c
> @@ -84,6 +84,10 @@ void replay_account_executed_instructions(void)
> if (replay_state.instructions_count > 0) {
> int count = (int)(replay_get_current_step()
> - replay_state.current_step);
> +
> + /* Time can only go forward */
> + assert(count >= 0);
> +
> replay_state.instructions_count -= count;
> replay_state.current_step += count;
> if (replay_state.instructions_count == 0) {
> --
> 2.11.0
Pavel Dovgalyuk
- [Qemu-devel] [PATCH v2 04/12] target/i386/misc_helper: wrap BQL around another IRQ generator, (continued)
- [Qemu-devel] [PATCH v2 04/12] target/i386/misc_helper: wrap BQL around another IRQ generator, Alex Bennée, 2017/04/05
- [Qemu-devel] [PATCH v2 06/12] cpus: check cpu->running in cpu_get_icount_raw(), Alex Bennée, 2017/04/05
- [Qemu-devel] [PATCH v2 01/12] scripts/qemugdb/mtree.py: fix up mtree dump, Alex Bennée, 2017/04/05
- [Qemu-devel] [PATCH v2 08/12] cpus: don't credit executed instructions before they have run, Alex Bennée, 2017/04/05
- [Qemu-devel] [PATCH v2 07/12] cpus: move icount preparation out of tcg_exec_cpu, Alex Bennée, 2017/04/05
- [Qemu-devel] [PATCH v2 09/12] cpus: introduce cpu_update_icount helper, Alex Bennée, 2017/04/05
- [Qemu-devel] [PATCH v2 12/12] replay: assert time only goes forward, Alex Bennée, 2017/04/05
- Re: [Qemu-devel] [PATCH v2 12/12] replay: assert time only goes forward,
Pavel Dovgalyuk <=
[Qemu-devel] [PATCH v2 11/12] cpus: call cpu_update_icount on read, Alex Bennée, 2017/04/05
[Qemu-devel] [PATCH v2 10/12] cpu-exec: update icount after each TB_EXIT, Alex Bennée, 2017/04/05