Re: [PATCH 7/7] migration: Finer grained tracepoints for POSTCOPY_LISTEN

[Dr. David Alan Gilbert]

* Peter Xu (peterx@redhat.com) wrote:
> The enablement of postcopy listening has a few steps, add a few tracepoints to
> be there ready for some basic measurements for them.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  migration/savevm.c     | 5 ++++-
>  migration/trace-events | 2 +-
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 17b8e25e00..5b3f31eab2 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1946,7 +1946,7 @@ static void *postcopy_ram_listen_thread(void *opaque)
>  static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
>  {
>      PostcopyState ps = postcopy_state_set(POSTCOPY_INCOMING_LISTENING);
> -    trace_loadvm_postcopy_handle_listen();
> +    trace_loadvm_postcopy_handle_listen(1);

I think we tend just to split this into separate traces in many places;
or if we're using the same one then we should use a string

I'd make this:
  trace_loadvm_postcopy_handle_listen_entry();

for example.

>      Error *local_err = NULL;
>  
>      if (ps != POSTCOPY_INCOMING_ADVISE && ps != POSTCOPY_INCOMING_DISCARD) {
> @@ -1962,6 +1962,7 @@ static int 
> loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
>              postcopy_ram_prepare_discard(mis);
>          }
>      }
> +    trace_loadvm_postcopy_handle_listen(2);
>  
>      /*
>       * Sensitise RAM - can now generate requests for blocks that don't exist
> @@ -1974,6 +1975,7 @@ static int 
> loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
>              return -1;
>          }
>      }
> +    trace_loadvm_postcopy_handle_listen(3);
>  
>      if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_LISTEN, &local_err)) {
>          error_report_err(local_err);
> @@ -1988,6 +1990,7 @@ static int 
> loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
>                         QEMU_THREAD_DETACHED);
>      qemu_sem_wait(&mis->listen_thread_sem);
>      qemu_sem_destroy(&mis->listen_thread_sem);
> +    trace_loadvm_postcopy_handle_listen(4);

  trace_loadvm_postcopy_handle_listen_entry_end();
>  
>      return 0;
>  }
> diff --git a/migration/trace-events b/migration/trace-events
> index d63a5915f5..1aa6937dc1 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -14,7 +14,7 @@ loadvm_handle_cmd_packaged_main(int ret) "%d"
>  loadvm_handle_cmd_packaged_received(int ret) "%d"
>  loadvm_handle_recv_bitmap(char *s) "%s"
>  loadvm_postcopy_handle_advise(void) ""
> -loadvm_postcopy_handle_listen(void) ""
> +loadvm_postcopy_handle_listen(int i) "%d"
>  loadvm_postcopy_handle_run(void) ""
>  loadvm_postcopy_handle_run_cpu_sync(void) ""
>  loadvm_postcopy_handle_run_vmstart(void) ""
> -- 
> 2.32.0
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK