Review Request: Implemented multithreading in KFileItemModelSortAlgorithm

[Emmanuel Pescosta]

> On Oct. 25, 2012, 12:17 p.m., Frank Reininghaus wrote:
> > Thanks for the new patch! 
> > 
> > I'm afraid it's a lot more complex than it needs to be. A recursive implementation like the one I suggested in
> > https://bugs.kde.org/show_bug.cgi?id=306290#c17 would be much simpler (and not that much different from the 2-thread solution you've posted earlier):
> > 
> > a) No need for your data structure ThreadList.
> > b) No loops.
> > c) No need to add complex code for parallel merging - you'd get that for free.
> > 
> > Maybe the reason for the rather insignificant performance increase is hidden somewhere in this complexity, I can't really say at first sight.
> > 
> > I don't know if you're still motivated to continue working on this, but I would very much prefer a straightforward recursive solution :-) 
> >

> Maybe the reason for the rather insignificant performance increase is hidden somewhere in this complexity, I can't really say at first sight.
It is faster (about 600 ms with 500.000 files) than the 2-thread implementation (The problem was the testing environment => Never run a cpu expensive background process while benchmarking :(

> I don't know if you're still motivated to continue working on this, but I would very much prefer a straightforward recursive solution :-) 
Yes I am still motivated! :) 

I have already done a n-thread recursive implementation (the code is very easy btw) based on my 2-thread implementation -> But this implementation was very very slow .... But I will try to speed it up ;)


- Emmanuel


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On Oct. 25, 2012, 11:48 a.m., Emmanuel Pescosta wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/107025/
> -----------------------------------------------------------
> 
> (Updated Oct. 25, 2012, 11:48 a.m.)
> 
> 
> Review request for Dolphin and Frank Reininghaus.
> 
> 
> Description
> -------
> 
> Implemented multithreading in KFileItemModelSortAlgorithm.
> 
> If more than 100 items to sort and ideal thread count is greater than 1 -> sort them with parallelSort (2 Threads)
> 
> Use maximal 2 Threads, because more than 2 Threads are "slower" (more overhead than speed up). (I also have a patch which uses n Threads for sorting, if you want test it ;)
> 
> 
> Diffs
> -----
> 
>   dolphin/src/kitemviews/private/kfileitemmodelsortalgorithm.h 3a596df 
>   dolphin/src/kitemviews/private/kfileitemmodelsortalgorithm.cpp e0aac13 
> 
> Diff: http://git.reviewboard.kde.org/r/107025/diff/
> 
> 
> Testing
> -------
> 
> About 2 seconds faster with sorting 500.000 files.
> About 5 seconds faster with sorting 1.000.000 files.
> 
> 
> Thanks,
> 
> Emmanuel Pescosta
> 
>

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