3 UDSEntry optimizations

[Milian Wolff]

On Thursday, July 23, 2015 10:15:20 PM Mark Gaiser wrote:
> On Sun, Jul 19, 2015 at 11:11 PM, Mark Gaiser <markg85 at gmail.com> wrote:
> > Hi,
> > 
> > I just pushed 3 UDSEntry changes to gerrit for your reviewing pleasure:
> >   1: https://gerrit.vesnicky.cesnet.cz/r/#/c/473/
> >   2: https://gerrit.vesnicky.cesnet.cz/r/#/c/474/
> >   3: https://gerrit.vesnicky.cesnet.cz/r/#/c/475/
> > 
> > The end result is a faster UDSEntry in every way. The benchmark results
> > (which are from udsentrybenchmark) can be found here:
> > http://kdeblog.mageprojects.com/?p=394&preview=1&_ppp=c936cdced4
> > 
> > So.. what did i do this time? Initially i wanted to get rid of the extra
> > bookkeeping without loss of speed or increasing memory usage. This was
> > basically an experiment to see if i could get that working. I was guessing
> > that a linear lookup (using std::find_if) would be equally fast as
> > QVector::contains(). That turned out to be that case as you can see in the
> > benchmarks.
> > 
> > Next up i wanted to use more advanced C++11 that QVector simply doesn't
> > allow: emplace_back:
> > http://en.cppreference.com/w/cpp/container/vector/emplace_back My guess
> > was that it would allow for quite some speedups in inserting because
> > objects would be created in place instead of created and copied (or
> > moved).
> > Looks like i was right since the benchmarks for creating entries have been
> > improved quite a bit.
> > 
> > While at it, also implemented move semantics :)
> > 
> > In terms of memory consumption these patches don't change much. Browsing a
> > massive folder (500.000 files) in dolphin without this patch series took
> > ~710MB, with it the figure was about 705MB. A saving, but nothing much
> > compared tot the total usage.
> > 
> > I would like to know what you folks think of these improvements.
> > I really wonder how much more performance i can squeeze out of UDSEntry.
> > 
> > Regarding gerrit. How can i make patch 2 and 3 dependent on 1?
> > And why is gerrit failing?
> > 
> > Best regards,
> > Mark
> 
> New benchmark link, the other one expired..
> http://kdeblog.mageprojects.com/?p=394&preview=1&_ppp=ae6e9e4851 (expires
> in one month)

What unit are these numbers in? How did you obtain them? You should make this 
as reproducible as possible, _and_ put this information /and/ the results into 
the individual commit messages. If someone will review the change in a few 
years down the road and cannot find this website, how should he figure out 
whether this is still applicable? Or if one wants to come up with some 
improvements, one needs documentation on how to do that. Mixing email, blog 
and commit messages is not a good idea. The commit message should be self 
consistent.

Bye

-- 
Milian Wolff
mail at milianw.de
http://milianw.de
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: This is a digitally signed message part.
URL: <http://mail.kde.org/pipermail/kde-core-devel/attachments/20150724/f65c871c/attachment.sig>