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From Daniel Shahaf <...@daniel.shahaf.name>
Subject Re: an observation regarding FSFS performance on BTRFS
Date Mon, 12 Sep 2011 16:07:18 GMT
1.7 includes performance optimizations by Stefan2, new cache modules,
new cache users, etc.

branches/performance includes, among other things, a file handles cache
for FSFS.  The plan is to merge that for 1.8.

branches/revprop-packing packs revprops into flat files (not to sqlite).
A basic form currently works and the final form will be included in 1.8.

Ben Smith-Mannschott wrote on Mon, Sep 12, 2011 at 17:28:28 +0200:
> I'm using 1.6.x. I wasn't aware that there'd been sufficient
> server-side work in 1.7.x as to make this distinction important.
> 
> // ben
> 
> On Mon, Sep 12, 2011 at 16:12, Daniel Shahaf <d.s@daniel.shahaf.name> wrote:
> > You haven't mentioned what version of svn you use.  As you say, there
> > has been work recently --- some of it is in 1.7, some of it is on
> > ^/subversion/branches/performance, some of it is on
> > ^/subversion/branches/revprop-packing, and some additional ideas
> > are in notes/fsfs-improvements.txt in trunk.
> >
> > Ben Smith-Mannschott wrote on Mon, Sep 12, 2011 at 15:44:20 +0200:
> >> I've made the observation that FSFS repositories perform better on
> >> EXT4 than BTRFS. This probably isn't ground-breaking, but I thought
> >> I'd share it.
> >>
> >> I've got two Linux machines:
> >>
> >> - colossus, using BTRFS spanned over two disks.
> >>   2.6.38-11-generic #48-Ubuntu SMP Fri Jul 29 19:02:55 UTC 2011
> >>   x86_64 x86_64 x86_64 GNU/Linux
> >>
> >> - oberon, using EXT4 on a 2-disk software RAID-1 set.
> >>   Linux oberon 2.6.32-33-generic #72-Ubuntu SMP Fri Jul 29 21:07:13 UTC 2011
> >>   x86_64 GNU/Linux
> >>
> >> I've noticed that writes to FSFS repositories are 5x faster under EXT4
> >> than BTRFS. When svnsyncing form the same svn:// source to an local
> >> repository (file://), oberon completes about 400 revisions in the time
> >> it takes colossus to grind through 80.
> >>
> >> The BTRFS machine is our build server. Performance with (1.6.x)
> >> working copies is quite acceptable, but I'm glad I'm not using it to
> >> host svn repositories.
> >>
> >> Looks like the BTRFS people have some work to do. Maybe current
> >> Kernels have already improved this picture. I know there has been
> >> recent work on reducing the cost of meta-data operations (e.g. file
> >> creation, ...) and that work is ongoing on defragmentation
> >> functionality because of poor performance on files that are modified
> >> in place heavily (e.g. sqlite).
> >>
> >> // ben
> >

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