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Re: [Qemu-block] [Qemu-devel] [PATCH] block: disable I/O limits at the b
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From: |
Eric Blake |
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Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH] block: disable I/O limits at the beginning of bdrv_close() |
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Date: |
Fri, 25 Sep 2015 08:22:26 -0600 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 |
On 09/25/2015 07:41 AM, Alberto Garcia wrote:
> Disabling I/O limits from a BDS also drains all pending throttled
> requests, so it should be done at the beginning of bdrv_close() with
> the rest of the bdrv_drain() calls before the BlockDriver is closed.
Can this be abused? If I have a guest running in a cloud where the cloud
provider has put severe throttling limits on me, but lets me hotplug to
my heart's content, couldn't I just repeatedly plug/unplug the disk to
get around the throttling (every time I unplug, all writes flush at full
speed, then I immediately replug to start batching up a new set of
writes). In other words, shouldn't the draining still be throttled, to
prevent my abuse?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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