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List: kfm-devel
Subject: Re: Review Request: Implemented multithreading in KFileItemModelSortAlgorithm
From: "Frank Reininghaus" <frank78ac () googlemail ! com>
Date: 2012-10-25 12:17:01
Message-ID: 20121025121701.7735.1011 () vidsolbach ! de
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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 :-)
- Frank Reininghaus
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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This is an automatically generated e-mail. To reply, visit:
<a href="http://git.reviewboard.kde.org/r/107025/">http://git.reviewboard.kde.org/r/107025/</a>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; \
white-space: -o-pre-wrap; word-wrap: break-word;">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 :-) </pre>
<br />
<p>- Frank</p>
<br />
<p>On October 25th, 2012, 11:48 a.m., Emmanuel Pescosta wrote:</p>
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<div>Review request for Dolphin and Frank Reininghaus.</div>
<div>By Emmanuel Pescosta.</div>
<p style="color: grey;"><i>Updated Oct. 25, 2012, 11:48 a.m.</i></p>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
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<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">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 ;)</pre> \
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
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#b8b5a0"> <tr>
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<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">About 2 seconds \
faster with sorting 500.000 files. About 5 seconds faster with sorting 1.000.000 files.</pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
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<li>dolphin/src/kitemviews/private/kfileitemmodelsortalgorithm.h <span style="color: \
grey">(3a596df)</span></li>
<li>dolphin/src/kitemviews/private/kfileitemmodelsortalgorithm.cpp <span style="color: \
grey">(e0aac13)</span></li>
</ul>
<p><a href="http://git.reviewboard.kde.org/r/107025/diff/" style="margin-left: 3em;">View \
Diff</a></p>
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