Re: [PATCH] Replace usage of schedYield with KeStallExecutionProcessor

[Paul Durrant <xadimgnik@xxxxxxxxx>]

On 08/09/2022 09:26, Rachel Yan wrote:
> From: Rachel Yan <Rachel.Yan@xxxxxxxxxx>
>
> ETW trace Transmitter DPC times show improvement of up to twice the speed
>
> Signed-off by: Rachel Yan <rachel.yan@xxxxxxxxxx>
> ---
>   src/xenbus/gnttab.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/xenbus/gnttab.c b/src/xenbus/gnttab.c
> index 33373c2..392f43d 100644
> --- a/src/xenbus/gnttab.c
> +++ b/src/xenbus/gnttab.c
> @@ -529,7 +529,7 @@ GnttabRevokeForeignAccess(
>           if (InterlockedCompareExchange16(flags, New, Old) == Old)
>               break;
>   
> -        SchedYield();
> +        KeStallExecutionProcessor(10);
Why 10, as opposed to some other random number? Surely just doing 
_mm_pause() would be simpler and have the same effect?
Also, can you please put the driver name in the subject line? I normally 
modify the .gitconfig in the repo to do this... In this case I can see 
from the name of the file which driver is being targetted, but that's 
not always the case. (And XENBUS doesn't have a 'Transmitter' so I think 
you really need more explanation in the commit comment too).
  Paul

>       }
>   
>       status = STATUS_UNSUCCESSFUL;