Re: [PATCH v3 7/8] migration: Finer grained tracepoints for POSTCOPY_LISTEN

[David Edmondson]

On Friday, 2021-12-24 at 14:49:59 +08, Peter Xu 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>

Reviewed-by: David Edmondson <david.edmondson@oracle.com>

> ---
>  migration/savevm.c     | 9 ++++++++-
>  migration/trace-events | 2 +-
>  2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 7f7af6f750..592d550a2f 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1947,9 +1947,10 @@ 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();
>      Error *local_err = NULL;
>
> +    trace_loadvm_postcopy_handle_listen("enter");
> +
>      if (ps != POSTCOPY_INCOMING_ADVISE && ps != POSTCOPY_INCOMING_DISCARD) {
>          error_report("CMD_POSTCOPY_LISTEN in wrong postcopy state (%d)", ps);
>          return -1;
> @@ -1964,6 +1965,8 @@ static int 
> loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
>          }
>      }
>
> +    trace_loadvm_postcopy_handle_listen("after discard");
> +
>      /*
>       * Sensitise RAM - can now generate requests for blocks that don't exist
>       * However, at this point the CPU shouldn't be running, and the IO
> @@ -1976,6 +1979,8 @@ static int 
> loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
>          }
>      }
>
> +    trace_loadvm_postcopy_handle_listen("after uffd");
> +
>      if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_LISTEN, &local_err)) {
>          error_report_err(local_err);
>          return -1;
> @@ -1990,6 +1995,8 @@ static int 
> loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
>      qemu_sem_wait(&mis->listen_thread_sem);
>      qemu_sem_destroy(&mis->listen_thread_sem);
>
> +    trace_loadvm_postcopy_handle_listen("return");
> +
>      return 0;
>  }
>
> diff --git a/migration/trace-events b/migration/trace-events
> index d63a5915f5..77d1237d89 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(const char *str) "%s"
>  loadvm_postcopy_handle_run(void) ""
>  loadvm_postcopy_handle_run_cpu_sync(void) ""
>  loadvm_postcopy_handle_run_vmstart(void) ""

dme.
-- 
If I could buy my reasoning, I'd pay to lose.