Re: [Qemu-devel] [RFC PATCH v4 17/25] cpus: make icount warp deterministic in replay mode

[Paolo Bonzini]

On 07/11/2014 11:33, Pavel Dovgalyuk wrote:
> This patch adds saving and replaying warping parameters in record and replay
> modes. These parameters affect on virtual clock values and therefore should
> be deterministic.

Why are QEMU_CLOCK_REALTIME timers not recorded/replayed like
QEMU_CLOCK_HOST is?

Paolo

> Signed-off-by: Pavel Dovgalyuk <address@hidden>
> ---
>  cpus.c |   24 +++++++++++++++++-------
>  1 files changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/cpus.c b/cpus.c
> index b41baf6..dac222b 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -370,7 +370,9 @@ static void icount_warp_rt(void *opaque)
>  
>      seqlock_write_lock(&timers_state.vm_clock_seqlock);
>      if (runstate_is_running()) {
> -        int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
> +        int64_t clock = qemu_clock_get_ns(replay_mode == REPLAY_MODE_NONE
> +                                          ? QEMU_CLOCK_REALTIME
> +                                          : QEMU_CLOCK_HOST);
>          int64_t warp_delta;
>  
>          warp_delta = clock - vm_clock_warp_start;
> @@ -444,7 +446,9 @@ void qemu_clock_warp(QEMUClockType type)
>      }
>  
>      /* We want to use the earliest deadline from ALL vm_clocks */
> -    clock = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
> +    clock = qemu_clock_get_ns(replay_mode == REPLAY_MODE_NONE
> +                              ? QEMU_CLOCK_REALTIME
> +                              : QEMU_CLOCK_HOST);
>      deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
>      if (deadline < 0) {
>          return;
> @@ -537,8 +541,10 @@ void configure_icount(QemuOpts *opts, Error **errp)
>          return;
>      }
>      icount_align_option = qemu_opt_get_bool(opts, "align", false);
> -    icount_warp_timer = timer_new_ns(QEMU_CLOCK_REALTIME,
> -                                          icount_warp_rt, NULL);
> +    icount_warp_timer = timer_new_ns(replay_mode == REPLAY_MODE_NONE
> +                                     ? QEMU_CLOCK_REALTIME
> +                                     : QEMU_CLOCK_HOST,
> +                                     icount_warp_rt, NULL);
>      if (strcmp(option, "auto") != 0) {
>          errno = 0;
>          icount_time_shift = strtol(option, &rem_str, 0);
> @@ -562,10 +568,14 @@ void configure_icount(QemuOpts *opts, Error **errp)
>         the virtual time trigger catches emulated time passing too fast.
>         Realtime triggers occur even when idle, so use them less frequently
>         than VM triggers.  */
> -    icount_rt_timer = timer_new_ms(QEMU_CLOCK_REALTIME,
> -                                        icount_adjust_rt, NULL);
> +    icount_rt_timer = timer_new_ms(replay_mode == REPLAY_MODE_NONE
> +                                   ? QEMU_CLOCK_REALTIME
> +                                   : QEMU_CLOCK_HOST,
> +                                   icount_adjust_rt, NULL);
>      timer_mod(icount_rt_timer,
> -                   qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + 1000);
> +                   qemu_clock_get_ms(replay_mode == REPLAY_MODE_NONE
> +                                     ? QEMU_CLOCK_REALTIME
> +                                     : QEMU_CLOCK_HOST) + 1000);
>      icount_vm_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
>                                          icount_adjust_vm, NULL);
>      timer_mod(icount_vm_timer,
>