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IDProjectCategoryView StatusDate SubmittedLast Update
0032014Open CASCADE[OCCT] OCCT:Data Exchangepublic2020-12-22 11:202020-12-22 11:22
Assigned Togka 
PrioritynormalSeverityjust a question 
PlatformWindowsOSVC++ 2015OS Version64 bit
Product Version[OCCT] 7.5.0 
Target Version[OCCT] 7.6.0*Fixed in Version 
Summary0032014: Data Exchange - large STEP file is read 2-3 times slower on msvc14 than on GCC and CLang
DescriptionReading a large 1GB STEP file shows enormous difference in time on different platforms (Windows 10 (msvc14), Ubuntu 18.04 (gcc7.5), macOS 10.14 (CLang11)):

|         | AMD Ryzen 3900X | Intel Core i5 |
|  msvc14 |      19:13      |     16:30     |
|  gcc7.5 |      06:13      |     14:54     |
| CLang11 |       N/A       |     07:31     |

gcc7.5 is 3x times faster than msvc14 on Ryzen 3900X (but not that much on Intel Core i5)
and CLang11 is 2x times faster than gcc7.5 and msvc14 on Intel Core i5.

Such a large difference (and extremely long STEP import time in case of msvc14 outsider) looks suspicious.

It is proposed to:
- Collect more data samples to verify if deviation is general or specific to one / few STEP files.
- Collect more statistics, including Visual Studio 2019, GCC 10 and CLang (Linux/Windows) to determine if difference is caused only by compiler or also by platform (dubious).
- Localize hot-spots in the algorithm showing most noticeable performance deviations and analyze options which would reduce the difference.
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- Relationships
related to 0032008verifiedbugmaster Modeling Algorithms - disallow implicit copy of Extrema algorithms 

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- Issue History
Date Modified Username Field Change
2020-12-22 11:20 kgv New Issue
2020-12-22 11:20 kgv Assigned To => gka
2020-12-22 11:21 kgv Relationship added related to 0032008
2020-12-22 11:22 kgv Description Updated View Revisions

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