Re: [PATCH v2 7/8] migration: Finer grained tracepoints for POSTCOPY_LISTEN

[Peter Xu]

On Tue, Dec 21, 2021 at 10:12:34AM +0000, David Edmondson wrote:
> On Monday, 2021-12-20 at 16:53:54 +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>
> > ---
> >  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..25face6de0 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 disgard");
> 
> s/disgard/discard/

Will fix.

> 
> > +
> >      /*
> >       * 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("exit");
> > +
> 
> "return" rather than "exit"?

I don't think it matters a lot, but sure.

Thanks,

-- 
Peter Xu