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From: | Anthony Liguori |
Subject: | Re: [Qemu-devel] [PATCH 0/3]: BLOCK_WATERMARK QMP event |
Date: | Tue, 09 Mar 2010 17:08:33 -0600 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Lightning/1.0pre Thunderbird/3.0 |
On 03/09/2010 04:53 PM, Luiz Capitulino wrote:
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.
The alternative way to implement this is for a management tool to just poll the allocated disk size periodically.
It's no more/less safe than generating an event on a "watermark" because the event is still racy with respect to a guest that's writing very quickly to the disk.
Regards, Anthony Liguori
It's a machine protocol, so I don't think the additional parameter matters much.
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