Determine Instrument Fraction

[Owen Arnold]

Question raised by Reflectometry group (Max). What proportion of the time for loading processed nexus files is occupied by reading of the instrument?

[Owen Arnold]

Using 'POLREF00004699_nexus.nxs' I obtained the following timings for the time taken to load the instrument definitions and spectrum maps as a fraction of the total load. I ran the same load 6 times clearing memory each time to avoid effects of instrument caching.

604 1717

752 2057

563 1787

584 1796

592 1797

590 1812

First column is for the instrument parts only.

This gives an average of 614.16 in the first column and 1827.67 in the second. As a result, the loading of the instrument takes almost exactly 1/3 of the total load time of LoadNexusProcessed

[Owen Arnold]

Tester. There are no (permanent) code changes as part of this. These results will be used for SSC reporting only. Verify that the results highlighted above seem reasonable.

[Owen Arnold]

Code changes for timings have been exported as a patch for reference.

[Harry Jeffery]

Using the same benchmark on my system I got 81±2 and 228±3, across six runs. The figures seem to hold up.

[Owen Arnold]

For completeness, Each workspace has 1 histogram, 5 bins and is 143 Kb in memory. Two workspaces in loaded group.

[Stuart Campbell]

This ticket has been transferred to github issue ​11758