I'm a simple iterative web server for a small project.  This web server 
uses regular read(2) and write(2) to both read file from the drive and
write it to the socket.

When I tested this web server on my FreeBSD 5.2.1 box, on a P IV 3 Ghz
Processor and 1 GB memory, I'm getting an enormous number of context
switches, as you can see below:

# vmstat 1
 procs      memory      page                    disks     faults      cpu
 r b w     avm    fre  flt  re  pi  po  fr  sr da0 da1   in   sy  cs us sy
id
 0 0 0  119644 736332    2   0   0   0   2   0   0   0  297    0 212  0  0
100
 0 0 0  119644 736332    4   0   0   0   4   0   0   0  294    0 200  0  0
100
 0 0 0  119644 736332    0   0   0   0   0   0   1   0  298    0 209  0  0
100
 0 0 0  119644 736348    0   0   0   0   4   0   4   0  308    0 303  0  1
99
 0 0 0  119644 736348    0   0   0   0   0   0   0   0  301    0 221  0  0
100
 0 0 0  119644 736348    0   0   0   0   0   0   0   0  300    0 215  0  0
100
 1 0 0  121336 736092   82   0   0   0  19   0   0   0 9203    0 50953  9 18
73
 1 0 0  121336 736040   13   0   0   0   0   0   0   0 18315    0 130743 14
46 40
 0 0 2  121336 735984   14   0   0   0   0   0   0   0 18514    0 128537 18
41 41
 1 0 0  121336 735928   14   0   0   0   0   0   0   0 20378    0 103812 15
40 45
 0 0 2  121336 735868   15   0   0   0   0   0   2   0 20029    0 107131 14
40 45
 0 0 2  121336 735804   16   0   0   0   0   0   4   0 22032    0 79700 17
33 50
 1 0 0  121336 735744   15   0   0   0   0   0   0   0 21645    0 87448 16
35 49
 0 0 1  121336 735684   15   0   0   0   0   0   0   0 20195    0 105555 17
39 44
 0 0 2  121336 735620   16   0   0   0   0   0   0   0 22129    0 81349 19
31 50
 0 0 1  121336 735564   14   0   0   0   0   0   5   0 20134    0 106842 19
36 45
 0 0 0  118992 736576   12   0   0   0 265   0   0   0 8283    0 58152  7 18
75
 0 0 0  118992 736576    0   0   0   0   0   0   0   0  295    0 197  0  1
99
 0 0 0  118992 736576    0   0   0   0   0   0   0   0  297    0 206  0  0
100
 0 0 0  118992 736576    0   0   0   0   0   0   0   0  296    0 201  0  0
100
 0 0 0  118992 736576    0   0   0   0   0   0   0   0  301    0 208  0  0
100
 0 0 0  118992 736576    0   0   0   0   0   0   0   0  294    0 198  0  0
100
 0 0 0  118992 736576    0   0   0   0   0   0   0   0  301    0 210  0  1
99
^C
#

When I run the same code on a Linux box, I'm only getting at most 33000 context
per second, thus it gives a better performance.

My question now is, is there a way I can trace the source of these context
switches, network, or disk? I'm thinking it may be disk, though it is also
possible that it is caused because of network.
Also, I tried testing the web server by using ramdisk, and the result is
still the same. The context switches stays around 100,000 at peak.

I'm hoping by reducing the number of context switches, I can increase my web
server performance. Oh by the way, again this web server is my own, and I
just use read(2), and write(2) to read and write to the socket, and to read
the file from the disk.

Thanks
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