Re: [Qemu-devel] [PATCH v5 2/4 for-3.0] qcow2: Options' documentation fixes

[Eric Blake]

On 07/26/2018 05:02 AM, Kevin Wolf wrote:
> Am 25.07.2018 um 16:27 hat Leonid Bloch geschrieben:
> > Signed-off-by: Leonid Bloch <address@hidden>
> > ---
> >   docs/qcow2-cache.txt |  3 +++
> >   qemu-options.hx      | 10 ++++++----
> >   2 files changed, 9 insertions(+), 4 deletions(-)

> > +++ b/qemu-options.hx
> > @@ -752,15 +752,17 @@ image file)
> >   
> >   @item cache-size
> >   The maximum total size of the L2 table and refcount block caches in bytes
> > -(default: 1048576 bytes or 8 clusters, whichever is larger)
>
> I think it would be good to still say something about the default.
> Maybe something like "default: the sum of l2-cache-size and
> refcount-cache-size"?

Except what happens if you specify only one of l2-cache-size or 
refcount-cache-size? Is the defaulted cache-size then just that one size 
you specified (and the other cache ignored), or is the total cache size 
still defaulted to the 1M/8-cluster size (assuming its larger than the 
other size specified)?

> >   @item l2-cache-size
> > -The maximum size of the L2 table cache in bytes
> > -(default: 4/5 of the total cache size)
> > +The maximum size of the L2 table cache.
>
> Why did you remove "in bytes" and add a period which the other options
> don't have? I prefer the old version of this line.
>
> > +(default: if cache-size is not defined - 1048576 bytes or 8 clusters, whichever
> > +is larger; otherwise, as large as possible or needed within the cache-size,
> > +while permitting the requested or the minimal refcount cache size)
> >   
> >   @item refcount-cache-size
> >   The maximum size of the refcount block cache in bytes
> > -(default: 1/5 of the total cache size)
> > +(default: 4 times the cluster size, or any portion of the cache-size, if it is
> > +specified and large enough, left over after allocating the full L2 cache)
>
> I found the second part hard to understand. Maybe "4 times the cluster
> size; or if both cache-size and l2-cache-size are given, the part of
> the cache-size that is not used for the L2 cache yet."?
>
> Kevin

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