Re: [Xen-devel] [PATCH] libxl: Wait for ballooning if free memory is increasing

[Wei Liu <wei.liu2@xxxxxxxxxx>]

You forgot go CC relevant maintainers. Now I've done that for you.

I think last time Ian and George were following.

On Wed, Jan 21, 2015 at 10:22:53PM -0700, Mike Latimer wrote:
> During domain startup, all required memory ballooning must complete
> within a maximum window of 33 seconds (3 retries, 11 seconds of delay).
> If not, domain creation is aborted with a 'failed to free memory' error.
> 
> In order to accommodate large domains or slower hardware (which require
> substantially longer to balloon memory) the free memory process should
> retry as long as the amount of free memory is increasing on each
> iteration of the loop.
> 
> ---
>  tools/libxl/xl_cmdimpl.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> index 0b02a6c..f87efc0 100644
> --- a/tools/libxl/xl_cmdimpl.c
> +++ b/tools/libxl/xl_cmdimpl.c
> @@ -2194,8 +2194,9 @@ static int preserve_domain(uint32_t *r_domid, 
> libxl_event *event,
>  
>  static int freemem(uint32_t domid, libxl_domain_build_info *b_info)
>  {
> -    int rc, retries = 3;
> -    uint32_t need_memkb, free_memkb;
> +    int rc, retries;
> +    const int MAX_RETRIES = 3;
> +    uint32_t need_memkb, free_memkb, free_memkb_prev = 0;
>  
>      if (!autoballoon)
>          return 0;
> @@ -2204,6 +2205,7 @@ static int freemem(uint32_t domid, 
> libxl_domain_build_info *b_info)
>      if (rc < 0)
>          return rc;
>  
> +    retries = MAX_RETRIES;
>      do {
>          rc = libxl_get_free_memory(ctx, &free_memkb);
>          if (rc < 0)
> @@ -2228,7 +2230,13 @@ static int freemem(uint32_t domid, 
> libxl_domain_build_info *b_info)
>          if (rc < 0)
>              return rc;
>  
> -        retries--;
> +        /* only decrement retry count if free_memkb is not increasing */
> +        if (free_memkb <= free_memkb_prev) {
> +            retries--;
> +        } else {
> +            retries = MAX_RETRIES;
> +            free_memkb_prev = free_memkb;
> +        }
>      } while (retries > 0);
>  
>      return ERROR_NOMEM;
> -- 
> 1.8.4.5
> 
> 
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