poll system call duration difference between RHEL5 and RHEL6

Issue

When analyzing the same application (same binary) executed on RHEL5 and on RHEL6, strange results
can be observed while doing statistics on the system calls durations :

Here is an example :

RHEL 5
------
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 98.56    6.599299         894      7379       290 poll
  0.51    0.034359           3     12465           write
  0.42    0.028436           6      4986           open
  0.26    0.017425           3      4990           munmap
  0.07    0.004692           2      2493           clone
  0.05    0.003651           1      5246           mmap2
  0.04    0.002361           1      2493           accept
  0.03    0.001894           0      4986           close
  0.03    0.001722           0      7479           gettimeofday
  0.01    0.000816           0      7479           fcntl64
  0.01    0.000629           0      4986           fstat64
  0.00    0.000196           0       795           mprotect
  0.00    0.000000           0       289       288 sigreturn
  0.00    0.000000           0       289           rt_sigaction
  0.00    0.000000           0       371        26 futex
------ ----------- ----------- --------- --------- ----------------
100.00    6.695480                 66726       604 total


RHEL 6
------
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 99.27   82.348662       11474      7177       293 poll
  0.15    0.126180           9     13320           write
  0.14    0.115069          22      5328           open
  0.10    0.079695          30      2643       720 futex
  0.07    0.057449          11      5328           munmap
  0.06    0.048710           6      7992           fcntl64
  0.05    0.038936           7      5664           mmap2
  0.04    0.036125           7      5328           fstat64
  0.04    0.030949           4      7992           gettimeofday
  0.03    0.028825           5      5328           close
  0.03    0.022025           8      2664           clone
  0.02    0.016268           6      2664           accept
  0.00    0.001762           6       295       293 sigreturn
  0.00    0.000515           2       295           rt_sigaction
  0.00    0.000176           1       336           mprotect
  0.00    0.000000           0         1           restart_syscall
  0.00    0.000000           0        21           brk
------ ----------- ----------- --------- --------- ----------------
100.00   82.951346                 72376      1306 total