Re: [Qemu-devel] [RFC PATCH v9 08/23] cpu: replay instructions sequence

[Paolo Bonzini <pbonzini@redhat.com>]

On 18/02/2015 12:56, Pavel Dovgalyuk wrote:
> This patch adds calls to replay functions into the icount setup block.
> In record mode number of executed instructions is written to the log.
> In replay mode number of istructions to execute is taken from the replay log.

So much better!  If there is a v10, please add a comment about how the
iothread is woken up---before the call to qemu_notify_event() and here
in the commit message.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Paolo

> Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
> ---
>  cpus.c          |   38 +++++++++++++++++++++++++-------------
>  replay/replay.c |   26 ++++++++++++++++++++++++++
>  replay/replay.h |    4 ++++
>  3 files changed, 55 insertions(+), 13 deletions(-)
> 
> diff --git a/cpus.c b/cpus.c
> index 04124ca..511a0c5 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -41,6 +41,7 @@
>  #include "qemu/seqlock.h"
>  #include "qapi-event.h"
>  #include "hw/nmi.h"
> +#include "replay/replay.h"
>  
>  #ifndef _WIN32
>  #include "qemu/compatfd.h"
> @@ -1306,6 +1307,28 @@ int vm_stop_force_state(RunState state)
>      }
>  }
>  
> +static int64_t tcg_get_icount_limit(void)
> +{
> +    int64_t deadline;
> +
> +    if (replay_mode != REPLAY_MODE_PLAY) {
> +        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
> +
> +        /* Maintain prior (possibly buggy) behaviour where if no deadline
> +         * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
> +         * INT32_MAX nanoseconds ahead, we still use INT32_MAX
> +         * nanoseconds.
> +         */
> +        if ((deadline < 0) || (deadline > INT32_MAX)) {
> +            deadline = INT32_MAX;
> +        }
> +
> +        return qemu_icount_round(deadline);
> +    } else {
> +        return replay_get_instructions();
> +    }
> +}
> +
>  static int tcg_cpu_exec(CPUArchState *env)
>  {
>      CPUState *cpu = ENV_GET_CPU(env);
> @@ -1319,24 +1342,12 @@ static int tcg_cpu_exec(CPUArchState *env)
>  #endif
>      if (use_icount) {
>          int64_t count;
> -        int64_t deadline;
>          int decr;
>          timers_state.qemu_icount -= (cpu->icount_decr.u16.low
>                                      + cpu->icount_extra);
>          cpu->icount_decr.u16.low = 0;
>          cpu->icount_extra = 0;
> -        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
> -
> -        /* Maintain prior (possibly buggy) behaviour where if no deadline
> -         * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
> -         * INT32_MAX nanoseconds ahead, we still use INT32_MAX
> -         * nanoseconds.
> -         */
> -        if ((deadline < 0) || (deadline > INT32_MAX)) {
> -            deadline = INT32_MAX;
> -        }
> -
> -        count = qemu_icount_round(deadline);
> +        count = tcg_get_icount_limit();
>          timers_state.qemu_icount += count;
>          decr = (count > 0xffff) ? 0xffff : count;
>          count -= decr;
> @@ -1354,6 +1365,7 @@ static int tcg_cpu_exec(CPUArchState *env)
>                          + cpu->icount_extra);
>          cpu->icount_decr.u32 = 0;
>          cpu->icount_extra = 0;
> +        replay_account_executed_instructions();
>      }
>      return ret;
>  }
> diff --git a/replay/replay.c b/replay/replay.c
> index a43bbbc..a6a5145 100755
> --- a/replay/replay.c
> +++ b/replay/replay.c
> @@ -58,3 +58,29 @@ uint64_t replay_get_current_step(void)
>  {
>      return cpu_get_icount_raw();
>  }
> +
> +int replay_get_instructions(void)
> +{
> +    int res = 0;
> +    replay_mutex_lock();
> +    if (skip_async_events(EVENT_INSTRUCTION)) {
> +        res = replay_state.instructions_count;
> +    }
> +    replay_mutex_unlock();
> +    return res;
> +}
> +
> +void replay_account_executed_instructions(void)
> +{
> +    if (replay_mode == REPLAY_MODE_PLAY
> +        && replay_state.instructions_count > 0) {
> +        int count = (int)(replay_get_current_step()
> +                          - replay_state.current_step);
> +        replay_state.instructions_count -= count;
> +        replay_state.current_step += count;
> +        if (replay_state.instructions_count == 0) {
> +            replay_has_unread_data = 0;
> +            qemu_notify_event();
> +        }
> +    }
> +}
> diff --git a/replay/replay.h b/replay/replay.h
> index a03c748..d19715f 100755
> --- a/replay/replay.h
> +++ b/replay/replay.h
> @@ -22,5 +22,9 @@ extern ReplayMode replay_mode;
>  
>  /*! Returns number of executed instructions. */
>  uint64_t replay_get_current_step(void);
> +/*! Returns number of instructions to execute in replay mode. */
> +int replay_get_instructions(void);
> +/*! Updates instructions counter in replay mode. */
> +void replay_account_executed_instructions(void);
>  
>  #endif
> 
> 
>