Re: [win-pv-devel] [PATCH 2/3] Prevent Schedule from preparing every outstanding SRB

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: win-pv-devel <win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf Of 
> Owen Smith
> Sent: 03 September 2019 15:43
> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Owen Smith <owen.smith@xxxxxxxxxx>
> Subject: [win-pv-devel] [PATCH 2/3] Prevent Schedule from preparing every 
> outstanding SRB
> 
> Returning a fail code from BlkifRingPostRequests will make the
> BlkifRingSchedule loop try a poll for responses, and exit the loop if
> no space is made available on the ring. This prevents the loop from
> proceeding to prepare the next queued SRB.
> 
> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
> ---
>  src/xenvbd/ring.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/src/xenvbd/ring.c b/src/xenvbd/ring.c
> index 74426f1..c8ad87d 100644
> --- a/src/xenvbd/ring.c
> +++ b/src/xenvbd/ring.c
> @@ -1132,12 +1132,11 @@ __BlkifRingPostRequests(
> 
>          InsertTailList(&BlkifRing->SubmittedList, ListEntry);
> 
> +        BlkifRing->Front.req_prod_pvt = req_prod;
>          if (RING_SLOTS_AVAILABLE(&BlkifRing->Front, req_prod, rsp_cons) <= 1)

Why <= 1?

> -            break;
> +            goto fail1;
>      }
> 
> -    BlkifRing->Front.req_prod_pvt = req_prod;
> -

Also this could stay here if you simply drop out of the loop with a break...

>      return STATUS_SUCCESS;

...and this was something like:

(enough ring slots available) ? STATUS_SUCCESS : STATUS_ALLOTTED_SPACE_EXCEEDED;

> 
>  fail1:

...and then I think you could get rid of this.

  Paul

> --
> 2.16.2.windows.1
> 
> 
> _______________________________________________
> win-pv-devel mailing list
> win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> https://lists.xenproject.org/mailman/listinfo/win-pv-devel
_______________________________________________
win-pv-devel mailing list
win-pv-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/win-pv-devel