Re: [Qemu-block] [PATCH v9 8/9] qcow2: Set the default cache-clean-interval to 10 minutes

[Alberto Garcia]

On Tue 18 Sep 2018 05:29:22 PM CEST, Leonid Bloch wrote:
>      /* New interval for cache cleanup timer */
>      r->cache_clean_interval =
>          qemu_opt_get_number(opts, QCOW2_OPT_CACHE_CLEAN_INTERVAL,
> -                            s->cache_clean_interval);
> +                            DEFAULT_CACHE_CLEAN_INTERVAL);

I just realized we're ignoring the old value (s->cache_clean_interval)
here. What's the consequence of this? (this was a change made by Kevin
Wolf in 5b0959a7d432062dcd740f8065004285b15695fa).

>  #ifndef CONFIG_LINUX
>      if (r->cache_clean_interval != 0) {
>          error_setg(errp, QCOW2_OPT_CACHE_CLEAN_INTERVAL
>                     " not supported on this host");

Another thing that I noticed (see below)...

> diff --git a/block/qcow2.h b/block/qcow2.h
> index 0f0e3534bf..8c863897b0 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -82,6 +82,7 @@
>  
>  #define DEFAULT_CLUSTER_SIZE S_64KiB
>  
> +#define DEFAULT_CACHE_CLEAN_INTERVAL 600  /* seconds */

Shouldn't this be set to 0 in non-Linux platforms? Otherwise it will try
to set it to 600 by default in all platforms and will complain with the
"not supported on this host" error message that I quoted above.

Berto