Kernel Memory Growth

[Pietro Paolini]

Hello everyone,

I am experiencing a problem using my Linux 2.6.33 and doing this networking test using ab, a tool from Apache which 
helps me to benchmark the performances of a website, actually I am using that as a tool for generate a lot of traffic and 
TCP connections.

My topology is :

[AB PC] <==> [LINUX] <==> [WEBSITE]

I run ab like that 

ab -c 300 -n 20000 http://10.0.0.103/index.html

and my problem is that after some time my system will reboot to a low memory condition, this is caused by the watchdog  I have installed in my system, I tried to monitor my applications but I did not see any growth in the memory
usage then I started to investigate if something is happening in the Kernel, using slab top I have got:

  OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME                   
 33392  33392 100%    1.00K   8348        4     33392K size-1024
  3716   3716 100%    4.00K   3716        1     14864K size-4096
 34238  33899  99%    0.20K   1802       19      7208K skbuff_head_cache
   547    538  98%    8.00K    547        1      4376K size-8192            
 12488  12488 100%    0.27K    892       14      3568K nf_conntrack_c0ca4b0c
 12990  12990 100%    0.12K    433       30      1732K size-128   
  2211   2211 100%    0.34K    201       11       804K inode_cache
 11387  11368  99%    0.06K    193       59       772K size-64   
    41     41 100%   16.00K     41        1       656K size-16384 
     4      4 100%  128.00K      4        1       512K size-131072
  2782   2702  97%    0.15K    107       26       428K dentry         
  4982   4957  99%    0.07K     94       53       376K sysfs_dir_cache
  8814   8558  97%    0.03K     78      113       312K size-32
   400    400 100%    0.50K     50        8       200K size-512
  1540   1255  81%    0.11K     44       35       176K vm_area_struct
   432    423  97%    0.30K     36       12       144K radix_tree_node

The first line 
 33392  33392 100%    1.00K   8348        4     33392K size-1024

tell me that size-1024 is using quite a lot of memory, how can I understand who is using that memory ?

Thanks in advance,
Pietro