Btrfs devel - Oct 2011 - Re: Patches for BTRFS (mail-server slow down in 3.0 and more)

On Oct 28, 2011, Marcel Lohmann <marcel@malowa.de> wrote:
> I would really appreciate if you could send me the patches.
Here are the patches I mentioned on IRC.  I''ve sent two of them to
Josef
for him to push upstream, but I''m not sure he posted them here for
I''m
not on the list (yet?).  The other two are newer, and the last one is
definitely not for inclusion (just for testing or as a temporary
work-around).

I''ve been using the first 3 with some success on a couple of mail
servers: I haven''t hit the ridiculous slow downs from frequent
unsuccessful calls of setup_cluster_no_bitmap after a while, like I did
with 3.0 (and 3.1) any more.

However, the excess use of metadata that I''ve experienced on ceph OSDs
isn''t fixed by them.  A btrfs balance with the first 3 still has 22GB
of
metadata block groups even though only 4.1GB of metadata are in use, or
19GB of metadata with only 2GB of metadata in use.  With the 4th patch
and -o clear_cache, the first rebalancing of the 22GB-metadata
filesystem got it down to 8GB; the second fs is still on rebalancing
~800GB (wishlist mental note: introduce some means to rebalance only the
metadata)

Here are the patches, against 3.1-libre (should apply cleanly on 3.1).











-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer

On Sat, Oct 29, 2011 at 02:35:16AM -0200, Alexandre Oliva
wrote:
> On Oct 28, 2011, Marcel Lohmann <marcel@malowa.de> wrote:
> 
> > I would really appreciate if you could send me the patches.
> 
> Here are the patches I mentioned on IRC.  I''ve sent two of them to
Josef
> for him to push upstream, but I''m not sure he posted them here for
I''m
> not on the list (yet?).  The other two are newer, and the last one is
> definitely not for inclusion (just for testing or as a temporary
> work-around).
The last one isn''t a bad idea, but please do make a real mount option
for it ;)

-chris
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On Oct 29, 2011, Chris Mason <chris.mason@oracle.com> wrote:
> The last one isn''t a bad idea, but please do make a real mount
option
> for it ;)
Like this?







-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer

On Mon, Oct 31, 2011 at 02:19:18AM -0200, Alexandre Oliva
wrote:
> On Oct 29, 2011, Chris Mason <chris.mason@oracle.com> wrote:
> 
> > The last one isn''t a bad idea, but please do make a real
mount option
> > for it ;)
> 
> Like this?
@@ -195,6 +195,7 @@ static match_table_t tokens = {
        {Opt_subvolrootid, "subvolrootid=%d"},
        {Opt_defrag, "autodefrag"},
        {Opt_inode_cache, "inode_cache"},
+       {Opt_nocluster, "nocluster"},
        {Opt_err, NULL},


How about ''no_alloc_cluster'' ? Or something suggesting
it''s related to
allocation. At least we''re not in situation of ocfs2 where are clusters
in
block-gouping- but also host-grouping sense, so I''m fine with
nocluster. Just
in case somebody has a better idea for the option name.


david
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On Oct 31, 2011, David Sterba <dave@jikos.cz> wrote:
> On Mon, Oct 31, 2011 at 02:19:18AM -0200, Alexandre Oliva wrote:
>> On Oct 29, 2011, Chris Mason <chris.mason@oracle.com> wrote:
>> 
>> > The last one isn''t a bad idea, but please do make a real
mount option
>> > for it ;)
>> 
>> Like this?
> @@ -195,6 +195,7 @@ static match_table_t tokens = {
>         {Opt_subvolrootid, "subvolrootid=%d"},
>         {Opt_defrag, "autodefrag"},
>         {Opt_inode_cache, "inode_cache"},
> +       {Opt_nocluster, "nocluster"},
>         {Opt_err, NULL},
> How about ''no_alloc_cluster'' ?
I considered that, too, but choosing the option name was the most
difficult part of the patch :-) I ended up going for the shorter name,
just to get the conversation started ;-) I don''t feel strongly about
it.

-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer
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