Re: [Xen-devel] [PATCH] xenpaging: use poll timeout if no paging target exists

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2012-08-28 at 09:32 +0100, Olaf Hering wrote:
> # HG changeset patch
> # User Olaf Hering <olaf@xxxxxxxxx>
> # Date 1346142745 -7200
> # Node ID b088e473c7fb1a47b9578693c1750cd27767cc25
> # Parent  03ef29089830b119b6efd87db8ab5c38b7428938
> xenpaging: use poll timeout if no paging target exists
> 
> Currently xenpaging will use 100% cpu time if a paging target is not yet
> set via xenstore. The reason is that ->use_poll_timeout is initialized
> to zero. Another case is when the paging target is set to zero. In this
> case ->use_poll_timeout will not be set to 1.
> 
> Fix the first case by initializing use_poll_timeout to 1 in
> xenpaging_init. The second case is fixed by setting use_poll_timeout in
> case the target is zero and there are no more pages left to resume.
> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
> 
> diff -r 03ef29089830 -r b088e473c7fb tools/xenpaging/xenpaging.c
> --- a/tools/xenpaging/xenpaging.c
> +++ b/tools/xenpaging/xenpaging.c
> @@ -482,6 +482,9 @@ static struct xenpaging *xenpaging_init(
>          goto err;
>      }
>  
> +    /* Use a poll timeout until xenpaging got a target from xenstore */
> +    paging->use_poll_timeout = 1;

Don't you want a negative (== infinite) timeout in this case?

> +
>      return paging;
>  
>   err:
> @@ -1019,6 +1022,8 @@ int main(int argc, char *argv[])
>          {
>              if ( paging->num_paged_out )
>                  resume_pages(paging, paging->num_paged_out);
> +            else
> +                paging->use_poll_timeout = 1;
>          }
>          /* Evict more pages if target not reached */
>          else if ( tot_pages > paging->target_tot_pages )
> 
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