On 7 April 2014 20:38, Stefan Fuhrmann <stefan.fuhrmann_at_wandisco.com> wrote:
> On Sun, Apr 6, 2014 at 5:36 PM, Ivan Zhakov <ivan_at_visualsvn.com> wrote:
>>
>> On 6 April 2014 18:31, Stefan Fuhrmann <stefan.fuhrmann_at_wandisco.com>
>> wrote:
>> > On Wed, Apr 2, 2014 at 12:13 PM, Ivan Zhakov <ivan_at_visualsvn.com> wrote:
>> >>
>> >> On 31 January 2014 14:57, Ivan Zhakov <ivan_at_visualsvn.com> wrote:
>> >> > On 31 January 2014 05:50, Evgeny Kotkov <evgeny.kotkov_at_visualsvn.com>
>> >> > wrote:
>> >> >>> This only affects non-sharded repositories with rev-local IDs,
>> >> >>> i.e. those in SVN 1.4 format. For those, it is writing 3 files
>> >> >>> instead of 2 per rev now.
>> >> >>
>> >> >> I assume you are talking about r1560723 [1]. If I read the code
>> >> >> correctly...
>> >> >> [[[
>> >> >> if ( (!max_files_per_dir || rev % max_files_per_dir == 0)
>> >> >> && dst_ffd->format >= SVN_FS_FS__MIN_NO_GLOBAL_IDS_FORMAT)
>> >> >> SVN_ERR(hotcopy_update_current(&dst_youngest, dst_fs, rev,
>> >> >> iterpool));
>> >> >> ]]]
>> >> >>
>> >> >> ...hotcopy now checkpoints after every revision for all non-sharded
>> >> >> repositories
>> >> >> with FSFS format >= 3. So, checkpointing happens for all FSFS
>> >> >> format
>> >> >> 1/2
>> >> >> repositories upgraded via 'svnadmin upgrade' (with linear layout),
>> >> >> that
>> >> >> were
>> >> >> not fsfs-reshard'ed or dump/loaded into a repository with newer
>> >> >> format.
>> >> >>
>> >> >> I am not aware of how many people reshard or dump/load their old
>> >> >> repositories
>> >> >> after upgrade, but I did a quick benchmark for a real-world
>> >> >> repository
>> >> >> and on my
>> >> >> machine it shows 7x performance degradation with checkpointing
>> >> >> enabled.
>> >> >> Is it
>> >> >> worth the ability to re-run the backup from a checkpoint upon
>> >> >> cancellation?
>> >> >>
>> >> >> [[[
>> >> >> # svnrdump http://googletest.googlecode.com/svn/trunk/
>> >> >> # load the dump into a --compatible-version=1.3 repository
>> >> >> # upgrade the repository with the most recent svnadmin
>> >> >>
>> >> >> # disable checkpointing, benchmark making 100 hotcopy backups:
>> >> >> real 0m18.741s
>> >> >> user 0m2.552s
>> >> >> sys 0m13.432s
>> >> >>
>> >> >> # now enable checkpointing and repeat the benchmark:
>> >> >> real 2m5.793s
>> >> >> user 0m0.836s
>> >> >> sys 0m34.840s
>> >> >> ]]]
>> >> >>
>> >> >> [1] http://svn.apache.org/viewvc?view=revision&revision=r1560723
>> >> >>
>> >> > That's what I suspected. In this case I think r1560723 should not be
>> >> > backported to 1.8.x for the following reasons:
>> >> > 1. Significant performance degradation for 'svnadmin hotcopy' with
>> >> > '--incremental' flag.
>> >> > 2. The change doesn't fix original circular dependency problem in
>> >> > FSFS
>> >> > 3. 'svnadmin recover' writes fake value to CURRENT file which very
>> >> > bad
>> >> > practice IMHO and could lead undefined consequences.
>> >> >
>> >> Hi Stefan,
>> >>
>> >> Is this problem fixed or it's better to revert r1560723 for reasons I
>> >> stated above?
>> >
>> >
>> > Hi Ivan,
>> >
>> > Evgeny applied his patch a month ago as r1573744.
>> >
>> Hi Stefan,
>>
>> Yes, I know. But svnadmin hotcopy performance regression was not fixed
>> as far I know.
>
>
> Oh - sorry!
> When I read your post, I didn't expand the quote.
>
> I don't have string feelings either way. As it makes
> laggards happy, I'm fine with the revert.
>
> Reverted in r1585516.
>
Thanks a lot!
--
Ivan Zhakov
Received on 2014-04-07 19:03:52 CEST