From: Fam Zheng <famz@redhat.com>
To: Elaye Karstadt <elayeek@gmail.com>
Cc: qemu-devel@nongnu.org, mreitz@redhat.com
Subject: Re: [Qemu-devel] qemu-img rebase working very slowly over NFS
Date: Wed, 25 Jan 2017 20:26:55 +0800 [thread overview]
Message-ID: <20170125122655.GE9699@lemon.Home> (raw)
In-Reply-To: <CABn57gE5rBetw0Di1a0S7M3LJOs5BWLi940a1wS+gBtVZ0z39g@mail.gmail.com>
On Wed, 01/25 08:35, Elaye Karstadt wrote:
> Two suggested solutions:
> 1. Before reading the old_backing and new_backing, one could call
> bdrv_is_allocated_above to check if a sector needs to be read (if a sector
> is not allocated in any file after new_backing, it can be assumed that it
> was not changed and need not be merged in the rebase?)
The rebase code is written such that it works even when moving an image from one
backing chain to another: reading and comparing data is simple and reliable for
that. But indeed your cases can be improved, just keep in mind any optimizations
for the specific "same chain" cases need to preserve the above property.
Fam
prev parent reply other threads:[~2017-01-25 12:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-25 8:35 [Qemu-devel] qemu-img rebase working very slowly over NFS Elaye Karstadt
2017-01-25 12:26 ` Fam Zheng [this message]
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=20170125122655.GE9699@lemon.Home \
--to=famz@redhat.com \
--cc=elayeek@gmail.com \
--cc=mreitz@redhat.com \
--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).