From: Alberto Garcia <berto@igalia.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
Max Reitz <mreitz@redhat.com>, Eric Blake <eblake@redhat.com>,
qemu-block@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] blockdev-add I/O throttling parameters
Date: Mon, 20 Feb 2017 17:29:19 +0100 [thread overview]
Message-ID: <20170220162919.GA21263@igalia.com> (raw)
In-Reply-To: <20170220154554.GF4814@noname.redhat.com>
On Mon, Feb 20, 2017 at 04:45:54PM +0100, Kevin Wolf wrote:
> > I can imagine two solutions that do not need these parameters in
> > blockdev-add:
> >
> > 1. I/O throttling is implemented by a BlockDriver. Users are expected
> > to create the BDS themselves. This is a little awkward since
> > query-block *does* include the throttling parameters in its output
> > and we must preserve this behavior for existing users.
> >
> > 2. block_set_io_throttle must be used after blockdev-add. Suboptimal
> > because issuing two commands is not atomic (use transaction?).
>
> The existing I/O throttling code is working on BlockBackends, but
> blockdev-add creates BlockDriverStates. So it can't possibly add
> throttling parameters.
>
> The currently recommended solution block_set_io_throttle. The
> other option to control BB level thorttling would be to add qdev
> properties to the block devices.
>
> In the long term, I think going with 1. and moving throttling to the
> block node level is the much nicer (and more flexible) option.
Yeah I agree with Kevin.
Berto
next prev parent reply other threads:[~2017-02-20 16:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-20 15:30 [Qemu-devel] blockdev-add I/O throttling parameters Stefan Hajnoczi
2017-02-20 15:45 ` Kevin Wolf
2017-02-20 16:29 ` Alberto Garcia [this message]
2017-02-21 11:17 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
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