Re: [Qemu-block] [PATCH v6 5/8] qcow2: Increase the default upper limit on the L2 cache size

[Eric Blake]

On 08/09/2018 04:53 PM, Leonid Bloch wrote:
> The upper limit on the L2 cache size is increased from 1 MB to 32 MB.
> This is done in order to allow default full coverage of an image with
> the L2 cache for images of up to 256 GB in size (was 8 GB). Note, that
> only the needed amount to cover the full image is allocated. The value
> which is changed here is just the upper limit on the L2 cache size,
> beyond which it will not grow, even if the size of the image requires
> it to.
>
> Signed-off-by: Leonid Bloch <address@hidden>
> ---
>   block/qcow2.h        | 2 +-
>   docs/qcow2-cache.txt | 6 +++---
>   qemu-options.hx      | 2 +-
>   3 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/block/qcow2.h b/block/qcow2.h
> index 0bab3d8b94..d77a31d932 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -73,7 +73,7 @@
>   /* Must be at least 4 to cover all cases of refcount table growth */
>   #define MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */
>   
> -#define DEFAULT_L2_CACHE_MAX_SIZE 1048576  /* bytes */
> +#define DEFAULT_L2_CACHE_MAX_SIZE 0x2000000U /* bytes */

I'd spell this as '(64 * MiB)' with the help of "qemu/units.h".

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org