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Re: [Qemu-devel] [PATCH 1/5] block/dirty-bitmap: add recording and busy
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 1/5] block/dirty-bitmap: add recording and busy properties |
Date: |
Tue, 12 Feb 2019 12:17:24 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 |
On 2/11/19 7:02 PM, John Snow wrote:
> The current API allows us to report a single status, which we've defined as:
>
> Frozen: has a successor, treated as qmp_locked, may or may not be enabled.
> Locked: no successor, qmp_locked. may or may not be enabled.
> Disabled: Not frozen or locked, disabled.
> Active: Not frozen, locked, or disabled.
>
> The problem is that both "Frozen" and "Locked" mean nearly the same thing,
> and that both of them do not intuit whether they are recording guest writes
> or not.
>
> This patch deprecates that status field and introduces two orthogonal
> properties instead to replace it.
> ---
No S-o-b?
> +++ b/qapi/block-core.json
> @@ -455,7 +455,13 @@
> #
> # @granularity: granularity of the dirty bitmap in bytes (since 1.4)
> #
> -# @status: current status of the dirty bitmap (since 2.4)
> +# @status: Deprecated in favor of @recording and @locked. (since 4.0)
I'd leave this one as (since 2.4). The deprecation clock is starting in
4.0, but the field has been present longer, and it is still obvious to
readers...
> +#
> +# @recording: true if the bitmap is recording new writes from the guest.
> +# Replaces `active` status. (since 4.0)
...that the replacement fields are only usable in 4.0 and newer.
> +#
> +# @busy: true if the bitmap is in-use by some operation (NBD or jobs)
> +# and cannot be modified via QMP right now. (since 4.0)
> #
> # @persistent: true if the bitmap will eventually be flushed to persistent
> # storage (since 4.0)
> @@ -464,6 +470,7 @@
> ##
> { 'struct': 'BlockDirtyInfo',
> 'data': {'*name': 'str', 'count': 'int', 'granularity': 'uint32',
> + 'recording': 'bool', 'busy': 'bool',
> 'status': 'DirtyBitmapStatus', 'persistent': 'bool' } }
The UI changes look reasonable.
No iotests coverage of "busy":true?
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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