How non-blocking kernel call is?

Discussion created by Raistmer on Sep 4, 2009
Latest reply on Sep 10, 2009 by Raistmer
Kernel call time depends from domain size

I measure time for kernel call itself.
That is, number of ticks spent from kernel call statement to return control to calling program, not time to completion kernel (i.e., not time when isSync( will return true).

As stated in brook manual kernel calls are async ones, that is they should return control "immediately".
But this "immediately" strongly depends from domain size on that kernelk was called.
Mean kernel call times vary from 7.68e+006 (with min=1.72e+005 and max=1.09e+008) to 1.19e+008 (min=2.25e+005 and max=9.77e+008).
Time in clock ticks, measured on Q9450@2.66GHz.
Domain size varied >~8 times.

Again, it's not kernel completion time, it's just time from starting kernel to moment when control was returned to program.

Why so strong domain size dependance for asynchronous call ???