Are you trying to time a program or function? If so the best way is to use the TSCL/TSCH registers. It is very easy and straight forward. see the following thread for details and links to examples:
http://e2e.ti.com/support/dsp/c6000_multi-core_dsps/f/639/t/130875.aspx#469012
csl_tmr.h is for accessing the device timer that can be used by the programs. for details see: http://www.ti.com/litv/pdf/sprugv5a
Regards,
Travis