Query for time tracking between userspace and kernelspace

[noman pouigt]

Hello,

Probably this question belongs to kernelnewbies
list but I think i will get accurate answer from here.

I am doing some optimization in kernel video driver
code to reduce the latency from the time buffer
is given to the time it is displayed.

Userspace:
t1 = gettimeofday()

Kernelspace:
t2 = do_gettimeofday()

Using debugfs i am copying t2 to userspace and
subtracting the result.

latency = t2 - t1

Would this be accurate? I know there is context
switch involved and other stuff but this is the method
i came up with. Any better way?

System: ARM (Android)
Kernel- 3.10
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