| |
|
 |
|
 |
|
|
|
| |
|
|
xen-users
[Xen-devel] Re: [RFC] tmem ABI change... backwards compatibility unneces
|
To: |
Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> |
|
Subject: |
[Xen-devel] Re: [RFC] tmem ABI change... backwards compatibility unnecessary? |
|
From: |
Vasiliy G Tolstov <v.tolstov@xxxxxxxxx> |
|
Date: |
Wed, 01 Sep 2010 18:44:08 +0400 |
|
Cc: |
Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "Xen-Devel \(xen-devel@xxxxxxxxxxxxxxxxxxx\)" <xen-devel@xxxxxxxxxxxxxxxxxxx>, tmem-devel@xxxxxxxxxxxxxx, kurt.hackel@xxxxxxxxxx, Jan Beulich <JBeulich@xxxxxxxxxx>, stephen.spector@xxxxxxxxxx, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, Chris, xen-users@xxxxxxxxxxxxxxxxxxx, Mason <chris.mason@xxxxxxxxxx> |
|
Delivery-date: |
Wed, 01 Sep 2010 07:47:41 -0700 |
|
Dkim-signature: |
v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=selfip.ru; s=dk; h=Content-Transfer-Encoding:Mime-Version:Message-ID:Date:Content-Type:References:In-Reply-To:Cc:To:Reply-To:From:Subject; bh=AyehzLMzE3+r4sGaNFqRr9NqMSSANVUZcWDjLaX3eGA=; b=MZd8kdg1aCcdhKOJpv+7F6ZjcLrFZR6tMjiHn06quou+cAvKXQKTJRCqYEn5Lem4OpEQg148SPnLSLTC8Sxoc9J8ffku/csdZRP+YfVHnaeayFi6L5HlVXTPQ5s9e9uA; |
|
Envelope-to: |
www-data@xxxxxxxxxxxxxxxxxxx |
|
In-reply-to: |
<1e601c02-1f50-4396-b4d1-e1e21ebf3dc8@default> |
|
List-help: |
<mailto:xen-devel-request@lists.xensource.com?subject=help> |
|
List-id: |
Xen developer discussion <xen-devel.lists.xensource.com> |
|
List-post: |
<mailto:xen-devel@lists.xensource.com> |
|
List-subscribe: |
<http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe> |
|
List-unsubscribe: |
<http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe> |
|
Organization: |
Selfip.Ru |
|
References: |
<1e601c02-1f50-4396-b4d1-e1e21ebf3dc8@default> |
|
Reply-to: |
v.tolstov@xxxxxxxxx |
|
Sender: |
xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
В Срд, 01/09/2010 в 07:36 -0700, Dan Magenheimer пишет:
> Tmem users and Xen developers/distros --
>
> (Please forward/repost as you see fit.)
>
> After a great deal of discussion and review with linux
> kernel developers, it appears there are "next-generation"
> filesystems (such as btrfs, xfs, Lustre) that will not
> be able to use tmem due to an ABI limitation... a field
> that represents a unique file identifier is 64-bits in
> the tmem ABI and may need to be as large as 192-bits.
> So to support these guest filesystems, the tmem ABI must be
> revised, from "v0" to "v1".
>
> I *think* it is still the case that tmem is experimental
> and is not used anywhere yet in production. If I am
> wrong, PLEASE LET ME KNOW ASAP.
>
> The tmem ABI is designed to support multiple revisions,
> so the Xen tmem implementation could be updated to
> handle both v0 and v1. However this is a bit
> messy and would require data structures for both v0
> and v1 to appear in public Xen header files.
>
> I am inclined to update the Xen tmem implementation
> to only support v1 and gracefully fail v0. This would
> result in only a performance loss (as if tmem were
> disabled) for newly launched tmem-v0-enabled guests,
> but live-migration between old tmem-v0 Xen and new
> tmem-v1 Xen machines would fail, and saved tmem-v0
> guests will not be able to be restored on a tmem-v1
> Xen machine. I would plan to update both pre-4.0.2
> and unstable (future 4.1) to only support v1.
>
> I believe these restrictions are reasonable at this
> point in the tmem lifecycle, though they may not
> be reasonable in the near future; should the tmem
> ABI need to be revised from v1 to v2, I understand
> backwards compatibility will be required.
>
> Comments or questions? (If agreeable, positive public
> acks appreciated.)
Thank You, Dan. What needed to do, to use tmem v1? Does it needed to
recompile dom0 kernel, or only domU kernel affected by change?
--
Vasiliy G Tolstov <v.tolstov@xxxxxxxxx>
Selfip.Ru
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home