HZ manipulation

I have 2.4.25 kernel from denx.de and latest uClibc running on mpc8248.
I'm trying to change HZ value, but still have strange results with simple test
Recompiling whole uClibc does not change the results.

What could be wrong?

with HZ==1000:
# alarm_test                                                                   

alarm fired after 0.099092s                                                    slept 0.999769s


with HZ==500:
# alarm_test                                                                   

alarm fired after 0.199622s                                                    slept 0.999761s

with HZ==100:
# alarm_test
alarm fired after 0.999693s
slept 0.999760s


- here is procesor id :

... by kernel:
# cat /proc/cpuinfo
processor       : 0
cpu             : 8280
core clock      : 400 MHz
CPM  clock      : 200 MHz
bus  clock      : 100 MHz
revision        : 32.20 (pvr 8082 2014)
bogomips        : 266.24

... and by u-boot:
MPC8248 Reset Status: External Soft, External Hard                            
                                                                               

MPC8248 Clock Configuration                                                    - Bus-to-Core Mult 4x, VCO Div 2, 60x Bus Freq  25-75 , Core Freq 100-300     - dfbrg 1, corecnf 0x1a, busdf 3, cpmdf 1, plldf 0, pllmf 3                   - vco_out  400000000, scc_clk  100000000, brg_clk   25000000                  - cpu_clk  400000000, cpm_clk  200000000, bus_clk  100000000                  - pci_clk   66666666                                                         
                                                                               

CPU:   MPC8248 (HiP7 Rev 14, Mask 1.0 1K50M) at 400 MHz


- test code included

Found it!

Sorry, It was my error.

I have few #ifdef-s to determine HZ value depend on  selected board,
but in some (for example itimer.c and timer.c) files <linux/config.h> is NOT included
before <asm/param.h> is included sowhere in the dark....
So some code was compiled with default value