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.

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.