We are seeing high CPU use in %system time. The server hits close to 100%, but no one process is taking up very much of the CPU.

Solution Verified - Updated -

Issue

  • Application team is seeing high response times in the mmap2 and unmap system calls leading to high %sys CPU time:
open("/dev/zero", O_RDONLY|O_LARGEFILE) = 6 <0.000014>
mmap2(NULL, 16777216, PROT_READ, MAP_PRIVATE, 6, 0) = 0xfffffffff10e9000 <0.005975>
close(6) = 0 <0.000015>
munmap(0xf10e9000, 16777216) = 0 <0.013544>
  • The mmap2 time running on this server is taking .006 and on rhel 4 physical it took .0001.

Environment

  • Red Hat Enterprise Linux, version 5.9
  • Oracle Tuxedo

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