Hi List,
I have a performance problem with my ext4 filesystem. In one directory,
the first time I run ls after a reboot, it takes more than two minutes.
Subsequent runs of the same command are very quick.
(The directory contains 54 files and one subdirectory, and it was first
created by git via a git-clone run.)
Details below.
Has anyone else seen similar behaviour?
/ johan
-------------------------
(squeeze on a laptop, / and /home on separate partitions, both are ext4
filesystems created by the debian installer)
After a reboot, and after letting gnome start normally, I cd to the
directory and run "strace -T ls". Almost every call reported takes less
than a millisecond, except one call to getdents on the current directory.
From the output of "strace -T ls", in a directory on the /home partition:
[...]
open(".", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 3 <0.000023>
fstat(3, {st_mode=S_IFDIR|0755, st_size=48648192, ...}) = 0 <0.000020>
fcntl(3, F_GETFD) = 0x1 (flags FD_CLOEXEC) <0.000015>
getdents(3, /* 57 entries */, 4096) = 2096 <152.245799>
getdents(3, /* 0 entries */, 4096) = 0 <0.000023>
close(3) = 0 <0.000030>
[..]
For a subsequent call to ls, the corresponding output is:
open(".", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 3 <0.000024>
fstat(3, {st_mode=S_IFDIR|0755, st_size=48648192, ...}) = 0 <0.000019>
fcntl(3, F_GETFD) = 0x1 (flags FD_CLOEXEC) <0.000015>
getdents(3, /* 57 entries */, 4096) = 2096 <0.059663>
getdents(3, /* 0 entries */, 4096) = 0 <0.000008>
close(3) = 0 <0.000009>
which is a factor of 3000 faster for the first call to getdents.
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