From: "Richard W.M. Jones" <rjones@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Fam Zheng <famz@redhat.com>, Hu Tao <hutao@cn.fujitsu.com>,
qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Yasunori Goto <y-goto@jp.fujitsu.com>
Subject: Re: [Qemu-devel] [PATCH v13 5/6] raw-posix: Add full preallocation option
Date: Thu, 4 Sep 2014 14:07:14 +0100 [thread overview]
Message-ID: <20140904130713.GC1302@redhat.com> (raw)
In-Reply-To: <20140904125257.GI3897@noname.str.redhat.com>
On Thu, Sep 04, 2014 at 02:52:57PM +0200, Kevin Wolf wrote:
> Am 04.09.2014 um 14:45 hat Richard W.M. Jones geschrieben:
> > On Thu, Sep 04, 2014 at 02:35:22PM +0200, Kevin Wolf wrote:
> > > Please change the code to always write zeros for FULL,
> >
> > How is this useful for anyone? You don't know if the underlying SAN
> > is going to detect these zeroes or combine these blocks together.
> > It's just slow for no reason.
>
> It's slow for the reason that the user has requested it. Do you doubt
> that users can know what their backend is doing? Why are you insisting
> on providing only the functionality that you personally need?
I'm not! I'm trying to make sure we don't end up with a qemu
interface which is useless for higher layers. You're proposing
preallocation=full which will be slow but not actually give any
guarantees, or preallocation=meta which is going to be fast but may
not work, and I'm saying that's a dumb interface that's not useful.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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next prev parent reply other threads:[~2014-09-04 13:07 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-29 8:33 [Qemu-devel] [PATCH v13 0/6] qcow2, raw: add preallocation=full Hu Tao
2014-08-29 8:33 ` [Qemu-devel] [PATCH v13 1/6] block: round up file size to nearest sector Hu Tao
2014-08-29 12:50 ` Eric Blake
2014-09-04 9:33 ` Kevin Wolf
2014-09-02 21:21 ` Max Reitz
2014-09-04 9:43 ` Kevin Wolf
2014-08-29 8:33 ` [Qemu-devel] [PATCH v13 2/6] block: don't convert file size to sector size Hu Tao
2014-09-02 21:24 ` Max Reitz
2014-09-04 9:57 ` Kevin Wolf
2014-09-05 9:07 ` Hu Tao
2014-08-29 8:33 ` [Qemu-devel] [PATCH v13 3/6] rename parse_enum_option to qapi_enum_parse and make it public Hu Tao
2014-09-02 21:27 ` Max Reitz
2014-09-03 1:30 ` Hu Tao
2014-09-04 10:03 ` Kevin Wolf
2014-08-29 8:33 ` [Qemu-devel] [PATCH v13 4/6] qapi: introduce PreallocMode and a new PreallocMode full Hu Tao
2014-09-02 21:32 ` Max Reitz
2014-09-03 1:31 ` Hu Tao
2014-09-02 21:51 ` Eric Blake
2014-09-03 1:35 ` Hu Tao
2014-09-04 12:17 ` Kevin Wolf
2014-08-29 8:33 ` [Qemu-devel] [PATCH v13 5/6] raw-posix: Add full preallocation option Hu Tao
2014-08-29 8:48 ` Richard W.M. Jones
2014-09-03 1:26 ` Hu Tao
2014-09-04 8:32 ` Hu Tao
2014-09-02 21:45 ` Max Reitz
2014-09-03 1:55 ` Hu Tao
2014-09-04 12:35 ` Kevin Wolf
2014-09-04 12:45 ` Richard W.M. Jones
2014-09-04 12:52 ` Kevin Wolf
2014-09-04 13:07 ` Richard W.M. Jones [this message]
2014-09-04 13:13 ` Daniel P. Berrange
2014-09-04 13:17 ` Kevin Wolf
2014-09-04 13:43 ` Richard W.M. Jones
2014-09-04 15:23 ` Kevin Wolf
2014-09-04 15:33 ` Richard W.M. Jones
2014-08-29 8:33 ` [Qemu-devel] [PATCH v13 6/6] qcow2: " Hu Tao
2014-09-02 21:55 ` Max Reitz
2014-09-04 13:09 ` Kevin Wolf
2014-09-09 3:23 ` Hu Tao
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