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From: Max Reitz <mreitz@redhat.com>
To: Eric Blake <eblake@redhat.com>,
	Denis Plotnikov <dplotnikov@virtuozzo.com>,
	qemu-block@nongnu.org
Cc: armbru@redhat.com, kwolf@redhat.com, famz@redhat.com,
	stefanha@redhat.com, jcody@redhat.com, qemu-devel@nongnu.org,
	den@virtuozzo.com, rkagan@virtuozzo.com
Subject: Re: [Qemu-devel] [PATCH v0 2/2] qmp: add block-set-copy-on-read command
Date: Wed, 13 Jun 2018 18:41:14 +0200	[thread overview]
Message-ID: <b78d2918-9ba8-5f4d-0953-bf2420aabae0@redhat.com> (raw)
In-Reply-To: <ebef7765-3ea7-b575-69ec-29ae66be561f@redhat.com>

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On 2018-06-13 18:02, Eric Blake wrote:
> On 06/13/2018 10:47 AM, Denis Plotnikov wrote:
>> The command enables/disables copy-on-read mode for VM's disk while
>> VM is running.
>>
>> This is needed when using external disk readers to shape access pattern
>> to the disk backend.
>>
>> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
>> ---
> 
> Deferring thoughts on the actual design for later;

But why? ;-)

This patch would definitely be superseded by a block reconfiguration
command (i.e. presumably one that makes reopen accessible over QMP).
With such a command, you could insert or remove a copy-on-read filter
node at any point in time.

Since we definitely want block graph configuration, I don't think we
want to add special commands now.

Max


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  reply	other threads:[~2018-06-13 16:41 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-13 15:47 [Qemu-devel] [PATCH v0 0/2] enable/disable copy-on-read via qmp Denis Plotnikov
2018-06-13 15:47 ` [Qemu-devel] [PATCH v0 1/2] block: check for read-only on copy-on-read setting Denis Plotnikov
2018-06-13 15:47 ` [Qemu-devel] [PATCH v0 2/2] qmp: add block-set-copy-on-read command Denis Plotnikov
2018-06-13 16:02   ` Eric Blake
2018-06-13 16:41     ` Max Reitz [this message]
2018-06-14  9:00       ` Kevin Wolf
2018-06-14  9:03         ` Alberto Garcia
2018-06-14  9:19           ` Kevin Wolf

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