Issue

• System call Futex is taking more time
• I am running strace command on a process

$ strace -c -f -p 8946

and following is the output:

% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 63.24  139.771752     1247962       112           select
 32.80   72.485283      609120       119        27 futex
  3.57    7.879802     3939901         2         2 restart_syscall
  0.22    0.482825           0   1979137           write
  0.11    0.237632           0   3951794           lseek
  0.06    0.127531         797       160           fsync
  0.01    0.020370         113       180           read
  0.00    0.008960         149        60        20 unlink
  0.00    0.002365           9       256           open
  0.00    0.000251           3       100        40 rename
  0.00    0.000139           1       256           close
  0.00    0.000139           3        50           stat
  0.00    0.000100           3        40           munmap
  0.00    0.000036           0        80           ftruncate
  0.00    0.000000           0        80           fstat
  0.00    0.000000           0        41           mmap
  0.00    0.000000           0         1           mprotect
  0.00    0.000000           0         5           madvise
  0.00    0.000000           0         5           clone
  0.00    0.000000           0         8           fcntl
  0.00    0.000000           0        64           getdents
  0.00    0.000000           0         5           set_robust_list
------ ----------- ----------- --------- --------- ----------------
100.00  221.017185               5932555        89 total

Futex system call is taking alomst 33% of time. We do not expect futex takes this much time.