Keywords: class-single-multiple

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### SYSTEM time

The SYSTEM time is the time spent in system Input/Output. In this context, it is roughly the time the Operating System spends to write the file on buffer/disk.

From fig. and fig. we can see that:

- the SYSTEM time has not changed between old and new CLASS output file types. This was expected since the size of the output file has not significatively changed.
- the SYSTEM time is proportional to the number of spectra written.
- the SYSTEM time is proportional to the number of channel per spectrum, when this number is high (typically more 1024 channels)
- on the other hand, there seems to be a threshold under which we cannot fall, e.g. writing spectra with 128 or 256 channels costs roughly the same SYSTEM time.

Finally, SYSTEM time is proportional to the amount of data written, and thus the file size. This is particularly true when this amount is high and hides over minor system actions.