some question about strace?

[loody]

hi all:
I have some questions about strace:
1. is there any filter condition I can set for filter out the time
interval > 0.5 sec?
take below for example, the time between set_thread_area and mprotect
is about 2.98 - 2.276 = 0.704 sec.
Is there any option can help me to find out this?
00:00:02.276000 set_thread_area(0x2aad2dc0) = 0 <0.000000>
00:00:02.980000 mprotect(0x2c4cc000, 32768, PROT_READ) = 0 <0.000000>

2. what are the difference between "strace" and "UST Userspace Tracer"?

-- 
Regards,
miloody