Hi,
I have a somewhat larger "directory entry" on this ext4 filesystem, and it
takes quite some time to list its contents:
------------------------------------
# time ls -lah /var/lib/php5
total 18M
drwxrwx--T. 6 root www-data 18M Apr 28 04:41 .
drwxr-xr-x. 48 root root 4.0K Apr 28 06:03 ..
drwxr-xr-x. 5 root root 4.0K Apr 28 04:41 modules
drwxr-xr-x. 2 www-data www-data 4.0K Oct 9 2014 owncloud-51d9c764244bc
drwxr-xr-x. 2 www-data www-data 4.0K Jan 6 23:27 owncloud-oc55674097b9
drwx-wx-wt. 2 root root 92K May 1 01:14 sessions
real 0m39.292s
user 0m0.000s
sys 0m3.964s
------------------------------------
Notice the "18M" entry for "." - I realize this is a directory for
temporary files, meaning that lots of files are generated here, but
the server is not _that_ busy; according to lsof(8) no files are
currently open in /var/lib/php5 and only the "sessions" directory
contains 100 files, there are far less files below the other directories.
Once the above is run, the next run of "ls" is fast, of course:
------------------------------------
# time ls -Rl /var/lib/php5 | wc -l
119
real 0m0.017s
user 0m0.004s
sys 0m0.008s
------------------------------------
There isn't really much content here, copying the structure to a new
directory results in ~450 KB of data.
I feel like this is some kind of FAQ, but I could not find anything
similar for Ext4. The only similar thing I could think of is an older
bug[0] in JFS, where a directory slowly grows when many files are
generated & deleted, but I could not reproduce this for Ext4.
The /var/lib/php5 directory from above is located on an Ext4 filesystem
from 2010, now running a 3.16 kernel (Debian/jessie, amd64), with the
following features as per tune2fs(8):
Filesystem features: has_journal ext_attr resize_inode dir_index
filetype needs_recovery extent sparse_super large_file uninit_bg
Filesystem flags: signed_directory_hash
Mount options:
/dev/sda1 on / type ext4 (rw,relatime,data=ordered)
Any pointers what's going on here?
Thanks,
Christian.
[0] https://bugzilla.kernel.org/show_bug.cgi?id=15154
--
BOFH excuse #268:
Neutrino overload on the nameserver
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