[Akonadi] [Bug 334218] synchronizations of large folders with filesystem contents hogs a Sandybridge core for minutes stat()ing every file in it
Martin Steigerwald
Martin at Lichtvoll.de
Fri May 2 12:33:27 BST 2014
https://bugs.kde.org/show_bug.cgi?id=334218
--- Comment #1 from Martin Steigerwald <Martin at Lichtvoll.de> ---
I bet that stat()ing files isnĀ“t the only issue here, as find -ls also uses a
variant of the stat() call on each file and as demonstrated it way faster:
Warm caches:
martin at merkaba:~/.local/share/local-mail/.Lichtvoll.directory/.Linux.directory>
strace -c find kernel-ml -ls 2>&1 >/dev/null
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
90.93 4.199983 17 250167 newfstatat
6.34 0.292629 770 380 getdents
1.97 0.091028 14 6437 write
0.60 0.027740 51 539 brk
0.04 0.001891 34 56 18 open
0.03 0.001159 27 43 mmap
0.02 0.000866 17 50 close
0.01 0.000650 17 38 fstat
0.01 0.000492 492 1 execve
0.01 0.000458 29 16 mprotect
0.01 0.000334 42 8 8 access
0.01 0.000323 36 9 munmap
0.01 0.000311 24 13 read
0.00 0.000180 45 4 4 connect
0.00 0.000176 10 17 fchdir
0.00 0.000150 21 7 openat
0.00 0.000121 30 4 socket
0.00 0.000095 19 5 lseek
0.00 0.000051 17 3 2 ioctl
0.00 0.000027 27 1 uname
0.00 0.000014 14 1 arch_prctl
------ ----------- ----------- --------- --------- ----------------
100.00 4.618678 257799 32 total
martin at merkaba:~/.local/share/local-mail/.Lichtvoll.directory/.Linux.directory>
/usr/bin/time find kernel-ml -ls 2>&1 >/dev/null
0.69user 0.35system 0:01.04elapsed 100%CPU (0avgtext+0avgdata
59536maxresident)k
0inputs+0outputs (0major+18011minor)pagefaults 0swaps
After echo 3 > /proc/sys/vm/drop_caches:
martin at merkaba:~/.local/share/local-mail/.Lichtvoll.directory/.Linux.directory>
/usr/bin/time find kernel-ml -ls 2>&1 >/dev/null
3.40user 9.67system 0:21.56elapsed 60%CPU (0avgtext+0avgdata 59532maxresident)k
780736inputs+0outputs (8major+18001minor)pagefaults 0swaps
(still just 20 seconds and well in case of KMail / Akonadi caches are warm,
machine has 8 GB of RAM)
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