### USER time vs SYSTEM time

We aim to track here where are the limitations depending on the context (number of channels per spectrum, number of spectrum per file).

Figure: USER vs SYSTEM time for the NEW and SINGLE CLASS output file types.

Fig. shows that:

- with the NEW file type, there was always a point where the USER time was equal to the SYSTEM time when writing more and more spectra (e.g. they were equal for 30,000 spectra of 4096 channels).
- in the same context, USER time became a limiting factor a high number of spectra, e.g. it was order of magnitude higher than the SYSTEM time when writing 524,288 spectra with 4,096 channels.
- the above point is not true anymore with the current version of CLASS, and the USER time is allways lower than the SYSTEM time (typically a half with 4,096 channels per spectrum).

We can conclude that now (on the test machine), the SYSTEM time is the limiting factor. The data rate is limited by both the hard disk driver (software) and its writing speed (hardware). There is no easy way to act on this time except from using a more performant hardware.