Questions Tagged With ram

Memory allocation in Linux

thinku — Sun, 02 May 2010 11:14:14 -0400

I got a doubt with memory allocation in Linux

I am having 256 MB of RAM in my portable player and the linux kernel is given with parameter "MEM=110M" while booting,

Can any one explain what does that mean

Is it a ...

1) 110 M is given for Kernel memory and remaining 146 is for user-space memory

or 2) 110M is given for kernel & user-space and remaining can be configured as per requirement (may be... say, driver memory)

Also, when i start a application that has many malloc in it., at some point the malloc() function returns null., whereas i parallely checking through Telnet for the "free memory space" through "free" cmd, it returns 39 MB as unused (ie., free)

I am little confused now (may be i am not knowing the memory partitions), can any one explain on this

Thanks in advance

Thanks Jlliagre, My free observation is here

> #free
>         total   used   free   shared   buffers  
    Mem: 106428   66560  39868   0        5240 
> #

" Jlliagre --- Malloc is allocating virtual memory while free is displaying RAM and SWAP usage "

fine, then does it mean that virtual memory for a process is fixed amount so that other processes will also get memory, instead of putting other processes running out of memory.

my concern is even-though free shows 39868 KB, it fails on malloc() of 2.5 MB

Weird memory issue

Yeeeev — Thu, 15 Apr 2010 13:21:08 -0400

Hi,
I have a very weird memory issue (as you may have guessed from the title :) ).
There's a discrepency between the memory accumulated by the various applications 
(using "ps -eF" to collect that) and the memory reported by system monitor/"free".
Basically, I have around 0.5GB of memory that is not occupied by any application, 
but is not free as well. (It is not used as cache as well)
I restarted X (logged out and in again), but it didn't help.

free's output:
                 total       used       free     shared    buffers     cached
    Mem:       4056964    2874328    1182636          0     481360     592220
    -/+ buffers/cache:    1800748    2256216
    Swap:      6723160      31412    6691748
and on the other hand:
    $ ps -eF | grep -v COMMAND | awk '{rsum+=$6}END{print rsum}'
    1309016
I'm running Ubuntu 9.10 64bit.
I had some zombie processes, but I killed their parent process and that made 
them go away (and freed up some memory, but not all that's missing)
Any ideas how to further debug this would be appreciated.

Thanks!

[Debian Base] Extra ram: What can I symlink to /dev/shm to improve system performance?

george — Wed, 14 Apr 2010 00:47:10 -0400

I am running mint 8 on a first gen netbook. I have already installed the max 2GB ram. Mint uses 200MB to 500MB on average use on my machine. I know that /dev/shm is a dynamic 'ram drive'. What can I symlink to improve performance? I am asking about this only and not about other performance improvements. Thank you very much.