SWAP problem

[patricksan]

Dear All,

I installed 9.10 and the swap is not working.
I read some posts but in my case it does not work.

Some information:

1. First, to see if it is being used:


patrick@sanubuntudesktop:~$ free -m
total used free shared buffers cached
Mem: 2937 1082 1855 0 75 667
-/+ buffers/cache: 338 2598
Swap: 902 0 902


2. Configuration on fdsik

patrick@sanubuntudesktop:~$ sudo fdisk -l

Disk /dev/sda: 74.1 GB, 74088185856 bytes
255 heads, 63 sectors/track, 9007 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000d0dfe

Device Boot Start End Blocks Id System
/dev/sda1 * 1 8892 71424958+ 83 Linux
/dev/sda2 8893 9007 923737+ 5 Extended
/dev/sda5 8893 9007 923706 82 Linux swap / Solaris


3. My configuration on /etc/fstab

patrick@sanubuntudesktop:~$ cat /etc/fstab
proc /proc proc defaults 0 0
# / was on /dev/sda1 during installation
UUID=7a8fd6c8-6087-4589-a3bf-110242f29d3a / ext4 errors=remount-ro 0 1
# swap was on /dev/sda5 during installation
/dev/sda5 none swap sw 0 0
/dev/scd0 /media/cdrom0 udf,iso9660 user,noauto,exec,utf8 0 0
/dev/fd0 /media/floppy0 auto rw,user,noauto,exec,utf8 0 0

I'm not using UUID, just because I did some mkswap.


5. I also did some tests like what is described on https://help.ubuntu.com/community/SwapFaq

sudo swapoff -a
sudo /sbin/mkswap /dev/sda5
sudo swapon -a

6. My meminfo:

patrick@sanubuntudesktop:~$ cat /proc/meminfo
MemTotal: 3008000 kB
MemFree: 1897832 kB
Buffers: 78148 kB
Cached: 683744 kB
SwapCached: 0 kB
Active: 539100 kB
Inactive: 509256 kB
Active(anon): 427528 kB
Inactive(anon): 16 kB
Active(file): 111572 kB
Inactive(file): 509240 kB
Unevictable: 0 kB
Mlocked: 0 kB
HighTotal: 2146248 kB
HighFree: 1163492 kB
LowTotal: 861752 kB
LowFree: 734340 kB
SwapTotal: 923696 kB
SwapFree: 923696 kB
Dirty: 72 kB
Writeback: 0 kB
AnonPages: 286460 kB
Mapped: 209148 kB
Slab: 38600 kB
SReclaimable: 29068 kB
SUnreclaim: 9532 kB
PageTables: 9844 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 2427696 kB
Committed_AS: 1338832 kB
VmallocTotal: 122880 kB
VmallocUsed: 2548 kB
VmallocChunk: 118496 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 4096 kB
DirectMap4k: 16376 kB
DirectMap4M: 892928 kB



Can somebody give me another direction to solve my problem, please?


Thanks,
Patrick

PS.: I'm running Ubuntu 9.1 on a VM.

[darkod]

Why do you think it's not working, because it says Used=0? That just means you have enough ram to run your tasks there at the moment. Mine swap is used 0 most of the time too (in fact haven't seen it used yet, but I'm not checking all the time).

[presence1960]

Why do you think it's not working, because it says Used=0? That just means you have enough ram to run your tasks there at the moment. Mine swap is used 0 most of the time too (in fact haven't seen it used yet, but I'm not checking all the time).

Darko is right. Swap is only used when needed. If RAM is running all your tasks you will rarely see swap used. Another thing to keep in mind is Linux uses memory quite differently than windows does, actually it uses memory much more efficiently than windows.

[patricksan]

You are all right.

I had to stress the box a lot to start to see progress.
So I change the value on:

sudo sysctl vm.swappiness=90

Then I could see it working.

What I also noticed, just to leave it here, there is a difference on

free -m and the System monitor.

Thanks for all help

Best regards,
Patrick