On 27.01.2016 13:08, Johan Corveleyn wrote:
On Mon, Sep 28, 2015 at 12:16 PM, <stef...@apache.org> wrote:
Author: stefan2
Date: Mon Sep 28 10:16:12 2015
New Revision: 1705646
URL: http://svn.apache.org/viewvc?rev=1705646&view=rev
Log:
Tune reorg strategy during the FSFS format7 packs such that it favors
checkout-style tree walks now.
Since r1703237, following the log history no longer requires frequent
access to directory data but mainly relies on noderev predecessor chain.
Therefore, it is no longer necessary to tightly pack directories in a
separate part of the pack file. With this patch, they are now placed
with the file contents and can be processed by a quasi-linear scan
instead of reading from two sections per pack.
* subversion/libsvn_fs_fs/pack.c
(compare_dir_entries_format7): Adapt reporting strategy - process dirs
at the same time as files now.
(compare_is_dir): No longer needed.
(sort_reps): No longer distinguish between file and dir reps but only
paths and delta chains when determining reprentation order.
Hi Stefan,
In this post-1.9.x-branch commit (and a couple of subsequent
pack-related commits) you changed the pack layout for FSFS format7, to
make it more efficient for exports, checkouts, ...
The benefit is not massive and very much depends on
project vs. repository size. 20% or so for SVN.
I'm wondering, when 1.10 comes out, how will I be able to benefit from
this improved pack layout? Supposing I've already dump/load-ed with
1.9 in FSFS7, and packed it.
Future commits will use the new strategy. So, speed
will slightly go up over time.
Does this require a format bump (and another dump/load)? Or do you
plan on providing a way to "repack" (or simply unpack and pack) a
packed repository? Currently there is no unpack or repack command ...
This is no format change; the beauty of format 7 is
that we can learn and tweak strategies as we go without
a format bump. OTOH, there is not much potential for
further improvement right now. FSFS is limited by its
fixed sharing scheme.
I have no *plans* for unpack/repack but the thought
has occurred to me. It should not be hard to do as
an offline operation, maybe alongside a reshard command.
If you want to write an 'svnadmin unpack', I'd support
you in that effort.
-- Stefan^2.
