Hi Lingxiao,
There is not direct equivalent of the "top" command for the dsp but the Code Composer studio profiler provides ability to check the number of times functions called, inclusive and exclusive total cycle each functions took to execute and number of simulator events within the functions. Other possibility of CCS profiler is to set up and use the profile clock in CCS to count instruction cycles between two points in the code. You can use these and many more abilities for dsp observations by CCS profiler. There are links to some instruction pages:
http://processors.wiki.ti.com/index.php/Profiler
http://processors.wiki.ti.com/index.php/Quick_Tips#Profiling.C2.A0
http://processors.wiki.ti.com/index.php/Profile_clock_in_CCS
BR
Tsvetolin Shulev