Bug 130184 - why does parallelized computing start up from 100 cells, for distributing on cores a power of two would be more reasonable?
Summary: why does parallelized computing start up from 100 cells, for distributing on ...
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Calc (show other bugs)
Version:
(earliest affected)
unspecified
Hardware: All All
: medium enhancement
Assignee: Not Assigned
URL:
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Keywords:
Depends on:
Blocks: OpenCL
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Reported: 2020-01-24 22:33 UTC by b.
Modified: 2023-05-08 20:31 UTC (History)
4 users (show)

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Description b. 2020-01-24 22:33:29 UTC
Description:

from playing around with bugs 124577 and 129753 i have the idea that the use of 'threaded' and / or 'openCL' computing is somewhere hardcoded to step in up from 100 rows with identical formulas, (former versions of calc had an option switch to choose the value), 

i assume that value is choosen to balance the perfomance benefit from parallelizing against the effort to divide and dispatch the jobs, 

but why 100? that's a logical threshold value for humans, but computers rely on powers of two? 

thus i think either 64 or 128 will fit better as decisive point whether to use or avoid parallelizing? or maybe other powers of two? 

as this area needs a workthrough anyway, to get out the autocalculate errors, it might be appropriate to process that in one wash? 

just an idea ... 

reg. 

b. 

Steps to Reproduce:
1. no real 'bug' to be seen, 
2. just an idea about meaningful design, 
3. analysis materil may be found in mentioned bug reports, 

Actual Results:
an arbitrary 'humane' value is established

Expected Results:
might be an 'computer fair' value would fit better? 


Reproducible: Always


User Profile Reset: No



Additional Info:
Version: 6.4.0.2 (x64)
Build ID: 08d19fecdc7a2298d051e19cfdb7c35544855fc3
CPU threads: 8; OS: Windows 6.1 Service Pack 1 Build 7601; UI render: default; VCL: win; 
Locale: de-DE (de_DE); UI-Language: en-US
Calc: CL
Comment 1 Julien Nabet 2020-01-25 09:25:28 UTC
Indeed it seems bound to 100
https://opengrok.libreoffice.org/xref/core/sc/source/core/tool/calcconfig.cxx?r=1d10db10#151
whereas it's bound to 2 for openCl unit test, see https://opengrok.libreoffice.org/xref/core/sc/source/core/tool/formulagroup.cxx?r=4704acf6#237


Tor: noticing https://cgit.freedesktop.org/libreoffice/core/commit/?id=a81a24b6a33fca9a750077d9160ebb8316b2fb26, thought you may have some idea here.
Personally, I've got no opinion here since I know too little about OpenCL.

Meanwhile, let's consider this as a possible enhancement more than a bug.