From: "Richard W.M. Jones" <rjones@redhat.com>
To: Hu Tao <hutao@cn.fujitsu.com>
Cc: Kevin Wolf <kwolf@redhat.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 v12 0/6] qcow2, raw: add preallocation=full and preallocation=falloc
Date: Mon, 25 Aug 2014 14:44:52 +0100 [thread overview]
Message-ID: <20140825134452.GU1302@redhat.com> (raw)
In-Reply-To: <20140825051830.GC25054@G08FNSTD100614.fnst.cn.fujitsu.com>
On Mon, Aug 25, 2014 at 01:18:30PM +0800, Hu Tao wrote:
> What if user cares about time(writing zeroes or non-zeroes is
> time-consuming) and wants falloc only sometimes? I think this is the
> main difference between preallocation=falloc and preallocation=full.
Also posix_fallocate in glibc falls back to writing zeroes when the
kernel/VFS doesn't support a true fallocate. So I'm afraid your patch
5/6 has a slow path, at least on common Linux distros.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine. Supports Linux and Windows.
http://people.redhat.com/~rjones/virt-df/
next prev parent reply other threads:[~2014-08-25 13:45 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-11 6:09 [Qemu-devel] [PATCH v12 0/6] qcow2, raw: add preallocation=full and preallocation=falloc Hu Tao
2014-07-11 6:09 ` [Qemu-devel] [PATCH v12 1/6] block: round up file size to nearest sector Hu Tao
2014-08-22 10:55 ` Kevin Wolf
2014-08-25 1:11 ` Hu Tao
2014-07-11 6:09 ` [Qemu-devel] [PATCH v12 2/6] raw, qcow2: don't convert file size to sector size Hu Tao
2014-07-11 6:10 ` [Qemu-devel] [PATCH v12 3/6] rename parse_enum_option to qapi_enum_parse and make it public Hu Tao
2014-07-11 6:10 ` [Qemu-devel] [PATCH v12 4/6] qapi: introduce PreallocMode and a new PreallocMode full Hu Tao
2014-08-22 10:57 ` Kevin Wolf
2014-08-25 1:12 ` Hu Tao
2014-07-11 6:10 ` [Qemu-devel] [PATCH v12 5/6] raw-posix: Add falloc and full preallocation option Hu Tao
2014-08-22 10:58 ` Kevin Wolf
2014-08-25 1:18 ` Hu Tao
2014-07-11 6:10 ` [Qemu-devel] [PATCH v12 6/6] qcow2: " Hu Tao
2014-07-11 21:07 ` Max Reitz
2014-08-22 11:00 ` Kevin Wolf
2014-08-25 1:36 ` Hu Tao
2014-07-28 8:48 ` [Qemu-devel] [PATCH v12 0/6] qcow2, raw: add preallocation=full and preallocation=falloc Hu Tao
2014-08-22 10:54 ` Kevin Wolf
2014-08-25 1:35 ` Hu Tao
2014-08-26 10:44 ` Stefan Hajnoczi
2014-08-28 5:04 ` Hu Tao
2014-08-22 12:25 ` Richard W.M. Jones
2014-08-22 12:36 ` Daniel P. Berrange
2014-08-22 13:13 ` Kevin Wolf
2014-08-22 13:26 ` Richard W.M. Jones
2014-08-22 14:20 ` Daniel P. Berrange
2014-08-22 15:22 ` Kevin Wolf
2014-08-22 15:34 ` Richard W.M. Jones
2014-08-22 15:39 ` Richard W.M. Jones
2014-08-22 15:53 ` Kevin Wolf
2014-08-22 16:00 ` Richard W.M. Jones
2014-08-25 5:18 ` Hu Tao
2014-08-25 10:31 ` Richard W.M. Jones
2014-08-25 13:44 ` Richard W.M. Jones [this message]
2014-08-26 5:27 ` Hu Tao
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140825134452.GU1302@redhat.com \
--to=rjones@redhat.com \
--cc=hutao@cn.fujitsu.com \
--cc=kwolf@redhat.com \
--cc=mreitz@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
--cc=y-goto@jp.fujitsu.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).