Re: [Qemu-block] [PATCH] qcow2: Optimize L2 table cache size based on image and cluster sizes

[Frank Myhr]

On 10/07/2016 06:56 AM, Alberto Garcia wrote:
> I would like to know what's the use case you (Frank, Ed)
> are thinking about:

> - Are we talking about command-line options, QMP, or both?

Command-line options alone are sufficient for my use case, which is configuring 
and starting VMs using libvirt.


> - Do you know the size of the disk image or you want to be able to set
>   the cache size without having access to that information? In other
>   words, what's preventing you from calculating the cache size that you
>   need?

I know the disk image size, and can set cache size in bytes. l2-cache-size=max 
would be a convenience feature, *especially if it could become the default*. 
Then I could forget thinking about whether the image is larger than the current 
8GB fully-cached threshold, and only have to calculate cache size in bytes in 
case of very large images, multiple backing files, or very tight memory.

Frank