[pacman-dev] [PATCH] Avoid stat call to determine is_directory if possible

[Dan McGee]

On Tue, Oct 5, 2010 at 5:13 PM, Dan McGee <dpmcgee at gmail.com> wrote:
> And looking closer at my numbers, did we not lose time here? If you
> through the read() calls out (which I left in only because that was
> the top time user), I should do some new timings or someone else
> should as well...

Slower it is! Non-truncated test output below after two warm up runs of each.

$ strace -c pacman -Ss pacman >/dev/null
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 21.41    0.000764           0     11056        23 open
 20.15    0.000719           0     21733           read
 19.53    0.000697           0     17602         1 access
 11.27    0.000402           0     11054           mmap
  9.84    0.000351           0     11009           munmap
  7.17    0.000256           0      6608         3 stat
  5.89    0.000210           0     11026           fstat
  4.74    0.000169           0     11033           close
  0.00    0.000000           0         1           write
  0.00    0.000000           0        19           mprotect
  0.00    0.000000           0        55           brk
  0.00    0.000000           0         8           rt_sigaction
  0.00    0.000000           0         1           rt_sigprocmask
  0.00    0.000000           0        13        13 ioctl
  0.00    0.000000           0         1           execve
  0.00    0.000000           0         2           uname
  0.00    0.000000           0         1           fcntl
  0.00    0.000000           0        20           getdents
  0.00    0.000000           0         1           getrlimit
  0.00    0.000000           0         1           geteuid
  0.00    0.000000           0         1           arch_prctl
  0.00    0.000000           0         3         1 futex
  0.00    0.000000           0         1           set_tid_address
  0.00    0.000000           0         1           set_robust_list
------ ----------- ----------- --------- --------- ----------------
100.00    0.003568                101250        41 total

dmcgee at galway ~/projects/pacman (master)
$ strace -c ./src/pacman/.libs/lt-pacman -Ss pacman >/dev/null
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 19.29    0.000790           0     21733           read
 17.80    0.000729           0     17602         1 access
 15.85    0.000649          32        20           getdents
 15.14    0.000620           0     11009           munmap
 11.33    0.000464           0     11072        39 open
  7.20    0.000295           0     11033           close
  6.74    0.000276           0     11026           fstat
  6.64    0.000272           0     11054           mmap
  0.00    0.000000           0         1           write
  0.00    0.000000           0         9         6 stat
  0.00    0.000000           0        19           mprotect
  0.00    0.000000           0        53           brk
  0.00    0.000000           0         8           rt_sigaction
  0.00    0.000000           0         1           rt_sigprocmask
  0.00    0.000000           0        13        13 ioctl
  0.00    0.000000           0         1           execve
  0.00    0.000000           0         2           uname
  0.00    0.000000           0         1           fcntl
  0.00    0.000000           0         1           getrlimit
  0.00    0.000000           0         1           geteuid
  0.00    0.000000           0         1           arch_prctl
  0.00    0.000000           0         3         1 futex
  0.00    0.000000           0         1           set_tid_address
  0.00    0.000000           0         1           set_robust_list
------ ----------- ----------- --------- --------- ----------------
100.00    0.004095                 94665        60 total