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Re: [LUG] Size of /proc/kcore

 
On Mon, 13 Sep 2010, Simon Waters wrote:


On 13/09/10 19:30, Gordon Henderson wrote:


Just to add confusion to the issue ;-) It's not an area I've really
tinkered with, but on my 32-bit Atom desktop, it's 1065349120 bytes. I
have 2GB of RAM and 2GB of swap configured.


It would be 2GB if the kernel could address it properly.  When I say it
is usually the size of physical memory I mean the size of physical
memory addressable by the kernel. I kind of assume everyone has a kernel
that can address all their machines physical memory, although there are
good reasons why you might not want things configured that way.

I assume Atom processors can use bigmem kernels if needed?!


Yes, it's a bigmem kernel - well HIGMEM4G:

  gordon @ yakko: zfgrep HIGHMEM /proc/config.gz
  # CONFIG_NOHIGHMEM is not set
  CONFIG_HIGHMEM4G=y
  # CONFIG_HIGHMEM64G is not set
  CONFIG_HIGHMEM=y

Output of top:

Mem:   2051752k total,  1907172k used,   144580k free,   278800k buffers
Swap:  2056316k total,     7196k used,  2049120k free,  1069228k cached
This is running 2.6.34 which I'm not happy with - it's spewed forth a CPU lockup a few times in it's history (90 day uptime, dual core HT atom) 

And to Dan: I did run a memory grabber program - to fill 'er up:

Mem:   2051752k total,  1999848k used,    51904k free,      940k buffers
Swap:  2056316k total,  1770724k used,   285592k free,    35556k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
25056 gordon    20   0 3070m 1.7g  144 S    0 85.4   0:07.51 qq


Stil the same:

gordon @ yakko: ls -lh /proc/kcore
-r-------- 1 root root 1016M Sep 13 21:08 /proc/kcore


Looking at the output of dmesg, I see:

  1151MB HIGHMEM available.
  887MB LOWMEM available.

So maybe it's only HIGHMEM it can see in a 32-bit box with > 1GB RAM..

Ah yes, same on a 4GB box:

  # ls -lh /proc/kcore
  -r-------- 1 root root 1016M 2010-09-13 21:10 /proc/kcore

(again, 32-bit)
So ignore my ramblings and have fun with your 64-bit boxes :) One of these days I'll work out if it's going to be any better for the rather generic stuff I do! 

Gordon

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