FILE: Documentation/filesystems/proc.txt
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 utime         user mode jiffies
 stime         kernel mode jiffies
 cutime        user mode jiffies with child's
 cstime        kernel mode jiffies with child's
 ...
 gtime         guest time of the task in jiffies
 cgtime        guest time of the task children in jiffies

this time unit change from jiffies to USER_HZ since 2.6, 
FILE: fs/proc/array.c
------------------------------
seq_put_decimal_ull(m, ' ', cputime_to_clock_t(utime));
seq_put_decimal_ull(m, ' ', cputime_to_clock_t(stime));
seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cutime));
seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cstime));
...
seq_put_decimal_ull(m, ' ', cputime_to_clock_t(gtime));
seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cgtime));