From: Kevin Wolf <kwolf@redhat.com>
To: Alberto Garcia <berto@igalia.com>
Cc: Anton Nefedov <anton.nefedov@virtuozzo.com>,
Denis Lunev <den@virtuozzo.com>,
"qemu-block@nongnu.org" <qemu-block@nongnu.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
Max Reitz <mreitz@redhat.com>
Subject: Re: [Qemu-devel] [RFC] Re-evaluating subcluster allocation for qcow2 images
Date: Fri, 28 Jun 2019 16:57:08 +0200 [thread overview]
Message-ID: <20190628145708.GN5179@dhcp-200-226.str.redhat.com> (raw)
In-Reply-To: <w51r27dixcm.fsf@maestria.local.igalia.com>
Am 28.06.2019 um 16:43 hat Alberto Garcia geschrieben:
> On Thu 27 Jun 2019 06:05:55 PM CEST, Denis Lunev wrote:
> > Please note, I am not talking now about your case with COW. Here the
> > allocation is performed on the sub-cluster basis, i.e. the abscence of
> > the sub-cluster in the image means hole on that offset. This is
> > important difference.
>
> I mentioned the possibility that if you have a case like 2MB / 64KB and
> you write to an empty cluster then you could allocate the necessary
> subclusters, and additionally fallocate() the space of the whole cluster
> (2MB) in order to try to keep it contiguous.
>
> With this we would lose the space saving advantage of having
> subclusters. But perhaps that would work for smaller cluster sizes (it
> would mitigate the fragmentation problem).
There seem to be use cases for both ways. So does this need to be an
option?
Kevin
next prev parent reply other threads:[~2019-06-28 15:01 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-27 13:59 [Qemu-devel] [RFC] Re-evaluating subcluster allocation for qcow2 images Alberto Garcia
2019-06-27 14:19 ` Denis Lunev
2019-06-27 15:38 ` Alberto Garcia
2019-06-27 15:42 ` Alberto Garcia
2019-06-28 9:20 ` Kevin Wolf
2019-06-28 9:53 ` Alberto Garcia
2019-06-28 10:04 ` Kevin Wolf
2019-06-28 13:19 ` Alberto Garcia
2019-06-28 14:16 ` Kevin Wolf
2019-06-28 16:31 ` Alberto Garcia
2019-06-27 16:05 ` Denis Lunev
2019-06-28 14:43 ` Alberto Garcia
2019-06-28 14:47 ` Denis Lunev
2019-06-28 14:57 ` Kevin Wolf [this message]
2019-06-28 15:02 ` Alberto Garcia
2019-06-28 15:03 ` Denis Lunev
2019-06-28 15:10 ` Alberto Garcia
2019-06-28 15:15 ` Kevin Wolf
2019-06-28 15:09 ` Kevin Wolf
2019-06-28 15:12 ` Alberto Garcia
2019-07-01 6:22 ` Kevin Wolf
2019-06-27 16:54 ` Kevin Wolf
2019-06-27 17:08 ` Denis Lunev
2019-06-28 16:32 ` Alberto Garcia
2019-07-11 14:08 ` Alberto Garcia
2019-07-11 14:32 ` Kevin Wolf
2019-07-11 14:56 ` Alberto Garcia
2019-06-28 12:57 ` Alberto Garcia
2019-06-28 13:03 ` Alberto Garcia
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=20190628145708.GN5179@dhcp-200-226.str.redhat.com \
--to=kwolf@redhat.com \
--cc=anton.nefedov@virtuozzo.com \
--cc=berto@igalia.com \
--cc=den@virtuozzo.com \
--cc=mreitz@redhat.com \
--cc=qemu-block@nongnu.org \
--cc=qemu-devel@nongnu.org \
/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).