RE: [PATCH 1/3] net/colo-compare.c: Create event_bh with the right AioContext

["Zhang, Chen" <chen.zhang@intel.com>]

> -----Original Message-----
> From: Lukas Straub <lukasstraub2@web.de>
> Sent: Thursday, April 9, 2020 2:34 AM
> To: qemu-devel <qemu-devel@nongnu.org>
> Cc: Zhang, Chen <chen.zhang@intel.com>; Li Zhijian
> <lizhijian@cn.fujitsu.com>; Jason Wang <jasowang@redhat.com>; Marc-
> André Lureau <marcandre.lureau@redhat.com>; Paolo Bonzini
> <pbonzini@redhat.com>
> Subject: [PATCH 1/3] net/colo-compare.c: Create event_bh with the right
> AioContext
> 
> qemu_bh_new will set the bh to be executed in the main loop. This causes
> problems as colo_compare_handle_event assumes that it has exclusive
> access the queues, which are also accessed in the iothread. It also assumes
> that it runs in a different thread than the caller and takes the appropriate
> locks.
> 
> Create the bh with the AioContext of the iothread to fulfill these
> assumptions.
> 

Looks good for me, I assume it will increase performance. Do you have related data?

Thanks
Zhang Chen

> Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> ---
>  net/colo-compare.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/colo-compare.c b/net/colo-compare.c index
> 10c0239f9d..1de4220fe2 100644
> --- a/net/colo-compare.c
> +++ b/net/colo-compare.c
> @@ -890,6 +890,7 @@ static void colo_compare_handle_event(void
> *opaque)
> 
>  static void colo_compare_iothread(CompareState *s)  {
> +    AioContext *ctx = iothread_get_aio_context(s->iothread);
>      object_ref(OBJECT(s->iothread));
>      s->worker_context = iothread_get_g_main_context(s->iothread);
> 
> @@ -906,7 +907,7 @@ static void colo_compare_iothread(CompareState *s)
>      }
> 
>      colo_compare_timer_init(s);
> -    s->event_bh = qemu_bh_new(colo_compare_handle_event, s);
> +    s->event_bh = aio_bh_new(ctx, colo_compare_handle_event, s);
>  }
> 
>  static char *compare_get_pri_indev(Object *obj, Error **errp)
> --
> 2.20.1