About kernel memory limit

[adheer chandravanshi]

Try this command:

dmesg | grep Memory

For  me the output is:
[    0.000000] Memory: 2007408k/2051636k available (4678k kernel code, 42932k reserved, 2124k data, 668k init, 1142332k highmem)

Look here for more details:
https://bbs.archlinux.org/viewtopic.php?id=14412

~ Adheer

From: geraint0923 at gmail.com
Date: Fri, 11 Nov 2011 13:28:53 +0800
Subject: Re: About kernel memory limit
To: geek at uniserve.com
CC: dhylands at gmail.com; kernelnewbies at kernelnewbies.org

Thanks. 
But I think that command 'free' just tell the memory used in kernel space and user space.It is still unknown to us that how much memory is used by kernel.



On Fri, Nov 11, 2011 at 1:15 PM, Dave Stevens <geek at uniserve.com> wrote:


Quoting Geraint Yang <geraint0923 at gmail.com>:






Hi Dave,

Thank you for your help !

Does it mean that I could use all of the memory my computer has? But one of

my classmates told me that kernel could only use 1G from a 4G

memory.computer...Is there anything I have misunderstood ?




I'm sitting in front of a Ubuntu box with 8G installed, uname -a shows:



Linux roger-System-Product-Name 3.0.0-12-generic #20-Ubuntu SMP Fri Oct 7 14:56:25 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux



so kernel 3 and free: shows

             total       used       free     shared    buffers     cached

Mem:       8192500    2907656    5284844          0     162060    1915540

-/+ buffers/cache:     830056    7362444

Swap:      7812092          0    7812092



so 2.9G of 8 in use



Dave












On Fri, Nov 11, 2011 at 4:58 AM, Dave Hylands <dhylands at gmail.com> wrote:




Hi,



On Thu, Nov 10, 2011 at 6:23 AM, Geraint Yang <geraint0923 at gmail.com>

wrote:

> Hi there,

> I am a newbie to Linux kernel programming. I am going to make a module

> which will cost much memory in kernel, I just want to know how much

> memory I can get by calling memory allocate API in kernel.



All of it.



>From kernel space, you can completely exhaust memory to the point of

making your system unusable.



>From kernel space you have vmalloc memory and kmalloc memory (plus a

couple other memory spaces). Depending on how things are configured,

it's possible to exhaust vmalloc memory even though there is memory

available to be kmalloc'd.



--

Dave Hylands

Shuswap, BC, Canada

http://www.davehylands.com










--

Geraint Yang

Tsinghua University Department of Computer Science and Technology










-- 

It is told that such are the aerodynamics and wing loading of the bumblebee that, in principle, it cannot fly...if all this be true...life among bumblebees must bear a remarkable resemblance to life in the United States.





-- John Kenneth Galbraith, in American Capitalism: The Concept of Countervailing Power







-- 
Geraint Yang 
Tsinghua University Department of Computer Science and Technology




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