Thrashing is caused by under allocation of the minimum 
number of pages required by a process, forcing it to 
continuously page fault. The system can detect thrashing by 
evaluating the level of CPU utilization as compared to the 
level of multiprogramming. It can be eliminated by reducing 
the level of multiprogramming.

Thrashing is a high paging activity.A process is thrashing
if it is spending more time with paging rather than execution.
Caused by:-
* global replacement algorithm.
* under allocation of the minimum 
  number of pages required by a process.
* very high degree of multiprogramming.
Eliminated by:-
*reducing level or degree of multiprogramming.
*use local replacement algorithm.
*while allocating check minimum sufficient frame required
for   a process.