[libtcas] Load/Volume Test on the very new libtcas

milkyjing

The TCAS files for testing are all large ones and somewhat complex (chunks are stored in a more random order in the time dimension).

Load Test



Additional Info
Size:   2.35 GB (2,526,669,312 bytes)
Index Streams:   216


Testing Result

Without cache support

initialization takes 21513 mm

chunk streams 216


total time for rendering 2327 frames 597250

I/O time 542349
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memory operation duration: 54901

initialization takes 18393 mm

chunk streams 216


total time for rendering 2327 frames 619059

I/O time 564365
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memory operation duration: 54703

initialization takes 34274 mm

chunk streams 216


total time for rendering 2327 frames 674127

I/O time 619003
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memory operation duration: 55124


With frame cache support

initialization takes 1794 mm


total time for rendering 2327 frames 491435

I/O time 458912
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memory operation duration: 32523

initialization takes 1809 mm


total time for rendering 2327 frames 448815

I/O time 416802
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memory operation duration: 32013

initialization takes 18050 mm


total time for rendering 2327 frames 590885

I/O time 555709
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memory operation duration: 35176


Volume Test



Additional Info
Size:   1.26 GB (1,356,047,664 bytes)
Index Streams:   225


Testing Result

Without cache support

initialization takes 1950 mm

chunk streams 225


total time for rendering 2339 frames 46176

I/O time 5658
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memory operation duration: 40518

initialization takes 2012 mm

chunk streams 225


total time for rendering 2339 frames 45318

I/O time 5982
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memory operation duration: 39336

initialization takes 1996 mm

chunk streams 225


total time for rendering 2339 frames 45568

I/O time 5707
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memory operation duration: 39861


With frame cache support

initialization takes 1981 mm


total time for rendering 2339 frames 32761

I/O time 6178
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memory operation duration: 26583

initialization takes 2090 mm


total time for rendering 2339 frames 34274

I/O time 6741
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memory operation duration: 27533

initialization takes 1966 mm


total time for rendering 2339 frames 33883

I/O time 6162
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memory operation duration: 27721

milkyjing

When the file is too large, the OS's default file cache support may not work, so even it is the second time to access the file, the speed will still be slow, (we can recognize that, most of the time is spent on the I/O), and when it comes to such large TCAS files, the locality of chunks is likely not to be maintained, so the file cache will be a bad idea (it will make the I/O even slower!)...

1. However, even when we are dealing with such large files, the time it spent on doing the in-memory things is still very little.
2. Even in such condition, the frame cache will still improve the overall performance.
3. To enjoy the OS's default file cache support, the TCAS file should better be less than 1GB, (which is still large enough for practical use), and with the cache, the performance of the second time access will be dramatically increased. If the file is larger than 2GB, the OS's default file cache support may not work.
4. Theoritically speaking, the maximum TCAS file that the libtcas can support is 16GB, which is large enough.
5. It is really a bad idea to store video frames as TCAS frames, both a waste of disc space and performance, since the TCAS file format is designed for discrete pixels (isolated objects).

milkyjing