Hello, been a while, dual CPU mobos

Ralph Doncaster ralph-Zd07PnzKK1IAvxtiuMwx3w at public.gmane.org
Tue Sep 7 03:15:59 UTC 2004


On Mon, 6 Sep 2004, Christopher Browne wrote:

> The economy of things normally is that if you have a system with a mere
> 512MB of RAM, it is almost certain that spending a couple hundred
> dollars to upgrade to 2GB of RAM will provide the cheapest and most
> effective performance upgrade.

There is no such thing as a "normal" system and nothing is "almost
certain".  Bumping the RAM in my POP server (>5000 entries in /etc/passwd)
from 1GB to 2GB isn't going to make a material difference:
ralph at ns ~$ free
             total       used       free     shared    buffers     cached
Mem:        905240     804992     100248          0      35316     478100
-/+ buffers/cache:     291576     613664
Swap:      2024168      60688    1963480
ralph at ns ~$ uptime
 10:45pm  up 96 days,  1:40,  5 users,  load average: 0.69, 0.87, 0.84

vmstat will give you a good idea of where (if any) system bottlenecks are.
   swap          io     system         cpu
 si  so    bi    bo   in    cs  us  sy  id
  0   0     0     2    4     4   2   2   3
  0   0     0     0  159    47   1   1  98
  0   0     0    52  254   183   1   9  90
  0   0   128     0  192    89   4   2  94
  0   0     0     0  224    98   5   6  89
  0   0   129     0  234    72   5   4  91
  0   0     0     0  222   117  17  18  66
  0   0     0    32  252   110   9   4  87
  0   0     0     0  190    89   4   2  94
  0   0     0     0  240   131  15   6  79
  0   0   128     0  163    60   0   3  97

I can see that my CPU is mostly idle, so upgrading my 1Ghz duron CPU isn't
going to make a difference.  There's not much disk I/O, so my software
RAID-1 setup is fine.  Performance-wise this server is running fine.

IMHO, the cheapest way to improve performance is through software.  I used
to run the pop server that came with Courier IMAP.  I now get more than
double the performance from nupop.  hdparm tuning and using noatime on
your filesystem will often give a big improvement to disk performance.
Also consider tmpfs for /tmp.  I backed out of using it on 2.4.24 due to
crashes, but will probably give it a shot on my next kernel upgrade.

Ralph Doncaster, IStop.com president
6042147 Canada Inc.
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