You are not logged in.
- Topics: Active | Unanswered
#1 2011-10-05 22:25:25
- RetroX
- Member
- Registered: 2009-10-17
- Posts: 106
[solved] Mount/unmount extremely slow (relatively)
When I first installed my system, mounting and unmounting took a relatively unnoticeable amount of time. Now, mounting a single volume takes about a minute or more per volume, even for tmpfs volumes. I don't seem to see any other performance problems with my system other than this.
The change happened rather suddenly after I shredded a partition on my drive with one run of bytes (the overall size was about 100 GiB, but I've written several times that onto my drive). If it makes any difference, the partition was the one that's right to the left of my root partition, but I doubt that anything flowed over. The disk seems to be operating fine, and when I mount from live CDs, it takes the normal time.
Has anyone ever experienced this kind of problem before? Do you know what I can do to fix it without reinstalling my system? I tried reinstalling both the linux and util-linux packages, but that didn't seem to help.
EDIT: Problem's been solved. To fix:
- Downgrade to util-linux 2.20-2.
- Save everything that you're working on.
- Run the following:
# echo 1 > /proc/sys/kernel/sysrq
# rm -rf /etc/mtab*
- Hold Alt + SysRq and then type out REISUB to reboot.
Last edited by RetroX (2011-10-08 19:09:26)
Offline
#2 2011-10-06 05:57:06
- bernarcher
- Forum Fellow
- From: Germany
- Registered: 2009-02-17
- Posts: 2,281
Re: [solved] Mount/unmount extremely slow (relatively)
Not sure if it really helps but have you tried reformatting this partition?
To know or not to know ...
... the questions remain forever.
Offline
#3 2011-10-06 12:15:58
- splondike
- Member
- Registered: 2008-10-19
- Posts: 16
Re: [solved] Mount/unmount extremely slow (relatively)
I'm not sure I'm knowledgeable enough to help too much, but you might like to have a look at the strace command to debug this. It lets you see what calls a program makes to the kernel. You can compare its output on your arch system to what your live CD gives you.
Mounting an ext2 disk on my machine produces this summary (the -c option). I got fairly varied output each time I ran the command, but hopefully yours is more consistent.
$ strace -c mount /dev/sdb2 /mnt/Backup/
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00 0.000018 1 18 mmap2
0.00 0.000000 0 101 read
0.00 0.000000 0 4 write
0.00 0.000000 0 20 6 open
0.00 0.000000 0 14 close
0.00 0.000000 0 1 execve
0.00 0.000000 0 3 time
0.00 0.000000 0 1 1 mount
0.00 0.000000 0 1 1 access
0.00 0.000000 0 3 brk
0.00 0.000000 0 2 1 ioctl
0.00 0.000000 0 1 umask
0.00 0.000000 0 11 10 readlink
0.00 0.000000 0 5 munmap
0.00 0.000000 0 1 uname
0.00 0.000000 0 7 mprotect
0.00 0.000000 0 91 _llseek
0.00 0.000000 0 2 prctl
0.00 0.000000 0 2 rt_sigprocmask
0.00 0.000000 0 5 3 stat64
0.00 0.000000 0 2 lstat64
0.00 0.000000 0 11 fstat64
0.00 0.000000 0 3 getuid32
0.00 0.000000 0 2 getgid32
0.00 0.000000 0 3 geteuid32
0.00 0.000000 0 2 getegid32
0.00 0.000000 0 1 set_thread_area
0.00 0.000000 0 1 fadvise64_64
0.00 0.000000 0 1 fstatat64
------ ----------- ----------- --------- --------- ----------------
100.00 0.000018 319 22 totalThe summary is probably more interesting initially, but the full dump may be useful later (replace -c with -C for the the full dump combined with the summary).
Edit:
Another similar program you might like to look at is ltrace, which shows library calls (this article put me onto it).
$ ltrace -c mount /dev/sdb2 /mnt/Backup
% time seconds usecs/call calls function
------ ----------- ----------- --------- --------------------
48.11 0.046996 46996 1 blkid_do_safeprobe
22.59 0.022073 49 445 strlen
15.04 0.014694 28 507 strncmp
3.45 0.003375 3375 1 mount
2.37 0.002319 2319 1 blkid_probe_set_device
2.10 0.002048 2048 1 mnt_update_table
1.21 0.001181 1181 1 blkid_free_probe
1.01 0.000989 26 37 __strdup
0.39 0.000383 383 1 mnt_update_set_fs
0.39 0.000382 76 5 __xstat64
0.37 0.000358 358 1 setlocale
0.29 0.000287 26 11 free
0.28 0.000278 139 2 open64
0.25 0.000247 123 2 close
0.20 0.000198 49 4 readlink
0.19 0.000181 25 7 __errno_location
0.14 0.000136 136 1 blkid_evaluate_spec
0.11 0.000109 27 4 strchr
0.11 0.000108 27 4 strtok
0.11 0.000104 26 4 sigdelset
0.10 0.000097 48 2 sigprocmask
0.09 0.000085 28 3 __snprintf_chk
0.08 0.000080 26 3 strrchr
0.07 0.000065 65 1 access
0.06 0.000060 30 2 sigfillset
0.06 0.000054 54 1 __lxstat64
0.05 0.000051 51 1 getuid
0.05 0.000050 50 1 mnt_fs_set_options
0.05 0.000049 49 1 umask
0.05 0.000047 47 1 geteuid
0.05 0.000047 47 1 blkid_new_probe
0.04 0.000040 40 1 blkid_probe_lookup_value
0.04 0.000039 39 1 blkid_probe_set_superblocks_flags
0.04 0.000037 37 1 blkid_probe_enable_superblocks
0.04 0.000036 36 1 mnt_new_fs
0.04 0.000035 35 1 getopt_long
0.03 0.000034 34 1 mnt_init_debug
0.03 0.000034 34 1 mnt_fs_set_source
0.03 0.000033 33 1 bindtextdomain
0.03 0.000032 32 1 mnt_fs_set_fstype
0.03 0.000032 32 1 mnt_free_update
0.03 0.000031 31 1 mnt_new_update
0.03 0.000031 31 1 textdomain
0.03 0.000030 30 1 malloc
0.03 0.000030 30 1 __cxa_atexit
0.03 0.000029 29 1 mnt_free_fs
0.03 0.000028 28 1 mnt_fs_set_target
0.03 0.000028 28 1 mnt_update_get_mflags
------ ----------- ----------- --------- --------------------
100.00 0.097690 1074 totalLast edited by splondike (2011-10-06 12:21:07)
Offline
#4 2011-10-06 20:07:49
- RetroX
- Member
- Registered: 2009-10-17
- Posts: 106
Re: [solved] Mount/unmount extremely slow (relatively)
bernarcher: I don't think that that will help, because the file system is sound. It applies to RAM disks, to, and nothing but mount seems to be affected. Plus, I'd rather not have to install unless my system is completely broken; at this point, it's not really worth reinstalling for a minor inconvenience that could possibly be fixable.
splondike: When mounting an ext4 volume, I get:
$ sudo strace -c mount /media/stuff
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
64.04 0.043333 8 5619 nanosleep
34.48 0.023331 23331 1 mount
0.95 0.000640 0 5633 close
0.17 0.000113 0 5620 5620 link
0.12 0.000078 0 11238 alarm
0.11 0.000076 0 5634 1 open
0.10 0.000066 0 11238 rt_sigaction
0.04 0.000030 0 5619 fcntl
0.00 0.000000 0 98 read
0.00 0.000000 0 10 6 stat
0.00 0.000000 0 9 fstat
0.00 0.000000 0 2 lstat
0.00 0.000000 0 91 lseek
0.00 0.000000 0 17 mmap
0.00 0.000000 0 10 mprotect
0.00 0.000000 0 3 munmap
0.00 0.000000 0 3 brk
0.00 0.000000 0 4 rt_sigprocmask
0.00 0.000000 0 2 1 ioctl
0.00 0.000000 0 2 1 access
0.00 0.000000 0 1 getpid
0.00 0.000000 0 1 execve
0.00 0.000000 0 1 uname
0.00 0.000000 0 1 unlink
0.00 0.000000 0 10 8 readlink
0.00 0.000000 0 3 umask
0.00 0.000000 0 3 getuid
0.00 0.000000 0 2 getgid
0.00 0.000000 0 3 geteuid
0.00 0.000000 0 2 getegid
0.00 0.000000 0 2 prctl
0.00 0.000000 0 1 arch_prctl
0.00 0.000000 0 1 fadvise64
0.00 0.000000 0 1 newfstatat
------ ----------- ----------- --------- --------- ----------------
100.00 0.067667 50885 5637 totalObviously, there are more calls here than in yours, but I think that it's simply due to the fact that it's ext4 instead of ext2. The abundance of sleep calls is also a bit disconcerting. The fact that the time is off is unsettling, though, especially:
# time umount /media/stuff
real 0m29.284s
user 0m0.010s
sys 0m0.080s
# time mount /media/stuff
real 0m29.353s
user 0m0.017s
sys 0m0.103s(note that strace took the same amount of time, but didn't actually display it)
So, the mount time isn't really what's wrong, but the shell? I just tried reinstalling bash and it didn't seem to do anything. I thought that the real time was just the user and system time added together, but it doesn't seem to be that way.
Offline
#5 2011-10-08 02:54:24
- splondike
- Member
- Registered: 2008-10-19
- Posts: 16
Re: [solved] Mount/unmount extremely slow (relatively)
That's quite a different output to mine. I mounted and unmounted my ext4 home partition from single user mode within arch and got the following:
Mount:
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00 0.016665 16665 1 mount
0.00 0.000000 0 10 read
0.00 0.000000 0 1 write
0.00 0.000000 0 15 open
0.00 0.000000 0 15 close
0.00 0.000000 0 1 link
0.00 0.000000 0 4 2 unlink
0.00 0.000000 0 1 execve
0.00 0.000000 0 1 getpid
0.00 0.000000 0 2 1 access
0.00 0.000000 0 1 rename
0.00 0.000000 0 3 brk
0.00 0.000000 0 3 umask
0.00 0.000000 0 2 gettimeofday
0.00 0.000000 0 9 7 readlink
0.00 0.000000 0 6 munmap
0.00 0.000000 0 1 fchmod
0.00 0.000000 0 7 mprotect
0.00 0.000000 0 1 _llseek
0.00 0.000000 0 1 prctl
0.00 0.000000 0 4 rt_sigprocmask
0.00 0.000000 0 19 mmap2
0.00 0.000000 0 9 6 stat64
0.00 0.000000 0 2 lstat64
0.00 0.000000 0 11 fstat64
0.00 0.000000 0 2 getuid32
0.00 0.000000 0 1 getgid32
0.00 0.000000 0 2 geteuid32
0.00 0.000000 0 1 getegid32
0.00 0.000000 0 1 fchown32
0.00 0.000000 0 2 fcntl64
0.00 0.000000 0 1 set_thread_area
------ ----------- ----------- --------- --------- ----------------
100.00 0.016665 140 16 totalUnmount:
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
-nan 0.000000 0 8 read
-nan 0.000000 0 1 write
-nan 0.000000 0 12 open
-nan 0.000000 0 12 close
-nan 0.000000 0 1 link
-nan 0.000000 0 4 2 unlink
-nan 0.000000 0 1 execve
-nan 0.000000 0 1 getpid
-nan 0.000000 0 1 oldumount
-nan 0.000000 0 1 1 access
-nan 0.000000 0 1 rename
-nan 0.000000 0 3 brk
-nan 0.000000 0 1 umask
-nan 0.000000 0 2 gettimeofday
-nan 0.000000 0 1 1 readlink
-nan 0.000000 0 4 munmap
-nan 0.000000 0 1 fchmod
-nan 0.000000 0 7 mprotect
-nan 0.000000 0 1 _llseek
-nan 0.000000 0 2 prctl
-nan 0.000000 0 4 rt_sigprocmask
-nan 0.000000 0 17 mmap2
-nan 0.000000 0 3 1 stat64
-nan 0.000000 0 2 lstat64
-nan 0.000000 0 9 fstat64
-nan 0.000000 0 3 getuid32
-nan 0.000000 0 2 getgid32
-nan 0.000000 0 3 geteuid32
-nan 0.000000 0 2 getegid32
-nan 0.000000 0 1 fchown32
-nan 0.000000 0 2 fcntl64
-nan 0.000000 0 1 set_thread_area
------ ----------- ----------- --------- --------- ----------------
100.00 0.000000 114 5 totalFar fewer syscalls in my output, and quite different ones too. I also note that the 'link' syscall in your output error-ed out every time. If you run it now with the -C option and -o <dump-file> options, then have a look in the output for the link calls, they should tell you why they're failing.
I notice my *stat commands are suffixed with 64 and yours aren't. I'm running a 32 bit machine, what architecture is yours? Also, what kernel version are you running (mine's 3.0) and what's the content of your /etc/fstab?
Offline
#6 2011-10-08 11:48:01
- nob.dir
- Member
- Registered: 2011-10-08
- Posts: 16
Re: [solved] Mount/unmount extremely slow (relatively)
Hi,
The problem is the util-linux package in version 2.20-3. I downgraded to 2.20-2 version, and it goes well now.
I added the bug(#26337): https://bugs.archlinux.org/task/26337.
nob.dir
Offline
#7 2011-10-08 19:09:07
- RetroX
- Member
- Registered: 2009-10-17
- Posts: 106
Re: [solved] Mount/unmount extremely slow (relatively)
nob.dir: Thank you so much. That did the trick; I posted exactly what I did in the first post so that people can figure out how to solve this if they happen to have it.
splondike: I'm running x86_64 right now. It's using the stat64 calls to emulate 64-bit so that your hardware isn't limited to 4 GiB in certain cases; they're just native in 64-bit. I'm also using linux 3.0.6 and my fstab is a cluttery mess. 
Offline
#8 2011-10-09 11:04:47
- splondike
- Member
- Registered: 2008-10-19
- Posts: 16
Re: [solved] Mount/unmount extremely slow (relatively)
nob.dir swings in to save the day with his first post 
. Thanks for the explanation about the *64 calls.
Offline
#9 2011-10-22 09:20:55
- atomisirsi
- Member
- Registered: 2011-03-18
- Posts: 2
Re: [solved] Mount/unmount extremely slow (relatively)
Did anybody test the behaviour with latest util-linux 2.20.1?
PS: Thanks for your solution, nob.dir! This problem was really annoying.
Offline
#10 2011-10-22 16:23:17
- falconindy
- Developer
- From: New York, USA
- Registered: 2009-10-22
- Posts: 4,111
- Website
Re: [solved] Mount/unmount extremely slow (relatively)
Did anybody test the behaviour with latest util-linux 2.20.1?
PS: Thanks for your solution, nob.dir! This problem was really annoying.
If you read the bug report, you'll see that the fix isn't related to util-linux.
Offline