Re: [Qemu-block] [Qemu-devel] [PATCH 2/4] docs: Fix an inaccuracy due to recent changes

[Eric Blake]

On 07/24/2018 07:17 AM, Leonid Bloch wrote:
> Signed-off-by: Leonid Bloch <address@hidden>
> ---
>   docs/qcow2-cache.txt | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
> index 8a09a5cc5f..a0a1267482 100644
> --- a/docs/qcow2-cache.txt
> +++ b/docs/qcow2-cache.txt
> @@ -97,9 +97,9 @@ need:
>      l2_cache_size = disk_size_GB * 131072
>      refcount_cache_size = disk_size_GB * 32768
>   
> -QEMU has a default L2 cache of 1MB (1048576 bytes) and a refcount
> -cache of 256KB (262144 bytes), so using the formulas we've just seen
> -we have
> +QEMU has a default L2 cache of 1MB (1048576 bytes) or 8 clusters (whichever
> +is larger) and a refcount cache of 256KB (262144 bytes), so using the
Looks suspicious; isn't the refcount cache size also dependent on the 
cluster size?
> +formulas we've just seen we have (assuming the L2 cache is 1MB):
>   
>      1048576 / 131072 = 8 GB of virtual disk covered by that cache
>       262144 /  32768 = 8 GB
--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org