Re: [Qemu-block] [PATCH v3 2/5] qcow2: Make the default L2 cache sufficient to cover the entire image

[Alberto Garcia]

On Wed 08 Aug 2018 03:58:02 PM CEST, Alberto Garcia wrote:
>  1) If l2-cache-size > l2_metadata_size, then make l2-cache-size =
>     l2_metadata_size. This is already useful on its own, even with the
>     current default of 1MB.
>
>  2) Increase the default to 32MB. This won't waste additional memory for
>     small images because of the previous patch, and will cover images up
>     to 256GB. If you have larger images you would need to increase
>     l2-cache-size manually if you want to cache all the L2 metadata.

Let's try this way: we had many users requesting us to add a new option
to set l2-cache-size=100%, but we never agreed on a good API. Patch (1)
would do precisely that (l2-cache-size=1T). Patch (2) changes the
default, which may be better and probably enough for many users, but
it's not what solves the problem.

Berto