About kernel memory limit

[Dave Stevens]

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
>



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