[Qemu-devel] Re: [PATCH 0/3]: BLOCK_WATERMARK QMP event

[Kevin Wolf <kwolf@redhat.com>]

Am 09.03.2010 23:53, schrieb Luiz Capitulino:
>  Hi,
> 
>  This series is based on a previous series submitted by Uri Lublin:
> 
> http://lists.gnu.org/archive/html/qemu-devel/2009-03/msg00864.html
> 
>  Details on the patches, except for this question: does it make sense to have
> a 'low' watermark for block devices?
> 
>  I think it doesn't, then the event (and the monitor accompanying command)
> should be called BLOCK_HIGH_WATERMARK. But this makes the event very
> unflexible, so I have called it BLOCK_WATERMARK and added parameters for the
> high/low watermark type.

When should a low watermark trigger? Images only ever grow, so testing
if the highest allocated block goes below some watermark would never
work (except for some unlikely special cases like deleting a snapshot
after which no new clusters have been allocated).

>  It's a machine protocol, so I don't think the additional parameter
> matters much.

I don't think anyone is ever going to use it, but it probably wouldn't
hurt either.

Kevin