On Thursday 10 December 2015 01:26:38 Pádraig Brady wrote: > I also noticed a lot of fcntl calls on XFS > (basically one per file), which I need to look further into: > $ strace -c find/find /usr/share >/dev/null > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 40.03 0.147809 1 151710 fcntl > 17.62 0.065069 1 63154 close > 14.52 0.053608 1 40071 newfstatat > 13.15 0.048547 1 35400 getdents
In my testing, fcntl() was called 8x for each directory traversed. It was mainly caused by the implementation of opendirat(). It calls set_cloexec_flag(), which calls fcntl() two times. Then it calls fdopendir(), which also calls fcntl() two times. fts_build() also calls set_cloexec_flag(). Then inside_dir() calls dup_cloexec(), which is fcntl (fd, F_DUPFD_CLOEXEC, 0). Perhaps some syscalls could be optimized out by using dup_cloexec() also in fts_build()? Kamil
