Date:	Tue, 24 Mar 2015 12:59:41 +0000
From:	"Zimmermann, Alexander" <Alexander.Zimmermann@...app.com>
To:	Wolfgang Rosner <wrosner@...net.de>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: One way TCP bottleneck over 6 x Gbit tecl aggregated link //
 Kernel issue

Hi Wolfgang,

> Am 23.03.2015 um 14:54 schrieb Wolfgang Rosner <wrosner@...net.de>:
> 
> Am Montag, 23. März 2015 10:25:33 schrieben Sie:
>> Hi Wolfgang,
>> 
>>> Am 23.03.2015 um 10:05 schrieb Wolfgang Rosner <wrosner@...net.de>:
>>> 
>>> Am Montag, 23. März 2015 03:33:17 schrieb Eric Dumazet:
>>>> On Mon, 2015-03-23 at 01:57 +0100, Wolfgang Rosner wrote:
>>>>> Are you ready to assist me on this track?
>>>> 
>>>> First check if the problem is already solved, using this git tree ?
>>>> 
>>>> http://git.kernel.org/cgit/linux/kernel/git/davem/net.git
>>> 
>>> Is it OK to use this 3.19 tag?
>>> https://kernel.googlesource.com/pub/scm/linux/kernel/git/davem/net.git/+/
>>> v3.19
>>> 
>>> 
>>> I see that head is v4.0-rc4
>>> I'm afraid that this might break other things.
>>> I think of aufs, which I need to get my clients nfsroot booted.
>> 
>> probably you can take a look on OverlayFS (instead of aufs) which
>> was introduced in kernel 3.18
>> 
>> Alex
> 
> 
> Hi Alex,
> 
> Thank you for the tip.
> But if it just were that easy as to have a look at it....
> 
> As far as I know, overlayfs only allows two layers, right?
> So for more complex trees, I could maybe stack them (so I hope).
> 
> To do so, at least I had to redesign my complete script which builds the 
> nfsroot mimics as shown below.
> 
> And as far as I could figure out, the representation of whiteouts is different 
> in aufs and in overlayfs. So I cannnot simply use my existing aufs branches 
> and stack them by overlayfs, without breaking the file/ whiteout consistency, 
> or can I?
> 

sorry about that, but I’ve no clue. I got rid of the overlay stuff last year.
I netboot my diskless machines via PXE, NFS readonly (expect home), and tmpfs for 
the rest. That’s it.

> 
> However, when making the decision in favour of aufs, the udba ("user direct 
> branch access") feature (and lack thereof in overlayfs) was the main reason 
> not to go for overlayfs:
> 
>> Changes to the underlying filesystems while part of a mounted overlay
>> filesystem are not allowed.  If the underlying filesystem is changed,
>> the behavior of the overlay is undefined,
> ( from https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt )
> 
> Is this going to change in the foreseeable future?
> Are you aware of any plans to implement UDBA in overlayfs?

I don’t follow the overlayfs development anymore.

> If so, I would be glad to participate in testing.
> 
> I could live without the udba feature for a limited test period.
> But I got used to the possibility to install packages in a package layer, fine 
> tune configuration in another layer and live test this on a parallel cluster 
> of 16 machines, without dropping off nfsroot each time.

I see. Your environment is much more complicated than mine.

Alex

> 
> Maybe, part of this funcitonality can be replaced by btrfs snapshotting.
> But nevertheless, it would end up as a comlepte redesign of my cluster setup.
> 
> 
> Wolfgang Rosner
> 
> 
> 
> ############################################################################
> 
> This is how my aufs mounts look like:
> 
> aufs-nfsroot-blade-001 on /cluster/nfs/nfsr/blade-001.crunchnet type aufs 
> (rw,relatime,si=88a4f4d462df4343)
>        0 rw id=64 path=/cluster/node_roots/wheezy-HD-2015_02_21/cow/cow_001
>        1 ro+wh id=65 path=/cluster/node_roots/wheezy-HD-2015_02_21/config
>        2 ro+wh id=66 path=/cluster/node_roots/wheezy-HD-2015_02_21/mask
>        3 ro+wh id=67 path=/cluster/node_roots/wheezy-HD-2015_02_21/pkg_std
>        4 ro id=68 path=/cluster/node_roots/wheezy-HD-2015_02_21/base
>        xino: /tmp/.aufs.xino
> 	:
> 	(repeated 16 times)
> 	:
> aufs-nfsroot-blade-016
> 
> 
> 
> plus 3 admin layers (writable for each intermediary layer)
> 
> 
> 
> root@...ncher:/cluster/etc/scripts/available# mount | grep aufs
> aufs-nfsroot-blade-001 on /cluster/nfs/nfsr/blade-001.crunchnet type aufs 
> (rw,relatime,si=88a4f4d462df4343)
> aufs-nfsroot-blade-002 on /cluster/nfs/nfsr/blade-002.crunchnet type aufs 
> (rw,relatime,si=88a4f4d3fe245343)
> aufs-nfsroot-blade-003 on /cluster/nfs/nfsr/blade-003.crunchnet type aufs 
> (rw,relatime,si=88a4f4d3fe9c5343)
> aufs-nfsroot-blade-004 on /cluster/nfs/nfsr/blade-004.crunchnet type aufs 
> (rw,relatime,si=88a4f4d467b53343)
> aufs-nfsroot-blade-005 on /cluster/nfs/nfsr/blade-005.crunchnet type aufs 
> (rw,relatime,si=88a4f4d47db69343)
> aufs-nfsroot-blade-006 on /cluster/nfs/nfsr/blade-006.crunchnet type aufs 
> (rw,relatime,si=88a4f4d4630bb343)
> aufs-nfsroot-blade-007 on /cluster/nfs/nfsr/blade-007.crunchnet type aufs 
> (rw,relatime,si=88a4f4d4586cc343)
> aufs-nfsroot-blade-008 on /cluster/nfs/nfsr/blade-008.crunchnet type aufs 
> (rw,relatime,si=88a4f4d458689343)
> aufs-nfsroot-blade-009 on /cluster/nfs/nfsr/blade-009.crunchnet type aufs 
> (rw,relatime,si=88a4f4d3fda97343)
> aufs-nfsroot-blade-010 on /cluster/nfs/nfsr/blade-010.crunchnet type aufs 
> (rw,relatime,si=88a4f4d3fe3be343)
> aufs-nfsroot-blade-011 on /cluster/nfs/nfsr/blade-011.crunchnet type aufs 
> (rw,relatime,si=88a4f4d3fe8cb343)
> aufs-nfsroot-blade-012 on /cluster/nfs/nfsr/blade-012.crunchnet type aufs 
> (rw,relatime,si=88a4f4d3fc90c343)
> aufs-nfsroot-blade-013 on /cluster/nfs/nfsr/blade-013.crunchnet type aufs 
> (rw,relatime,si=88a4f4d4622fb343)
> aufs-nfsroot-blade-014 on /cluster/nfs/nfsr/blade-014.crunchnet type aufs 
> (rw,relatime,si=88a4f4d3e2cc8343)
> aufs-nfsroot-blade-015 on /cluster/nfs/nfsr/blade-015.crunchnet type aufs 
> (rw,relatime,si=88a4f4d0ca64e343)
> aufs-nfsroot-blade-016 on /cluster/nfs/nfsr/blade-016.crunchnet type aufs 
> (rw,relatime,si=88a4f4d0ca92e343)
> aufs_pkg_std on /cluster/node_roots/wheezy-HD-2015_02_21/admount-pkg_std type 
> aufs (rw,relatime,si=88a4f4d46dced343)
> aufs_mask on /cluster/node_roots/wheezy-HD-2015_02_21/admount-mask type aufs 
> (rw,relatime,si=88a4f4d3b0a2b343)
> aufs_config on /cluster/node_roots/wheezy-HD-2015_02_21/admount-config type 
> aufs (rw,relatime,si=88a4f4d3fee4c343)
> 
> 
> 
> 
> 
> 
> 

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