[hobbit] Hobbit Server performance

[Henrik Stoerner]

On Wed, Aug 29, 2007 at 04:14:58PM -0500, Jeff Newman wrote:
> The server is a DL360 G3 with two 3ghz processors and 2gb of RAM. It does only
> hobbit and cricket (10 or so routers, so not a huge hit)
> 
> I've noticed the following two things:
> 
> #1. I am constantly using 100% of my physical ram (no swap really)
> 
> Mem:   2075040k total,  2051928k used,    23112k free,    52172k buffers
> Swap:        0k total,        0k used,        0k free,  1744168k cached
> 
> is this normal? Not sure how to tell which process specifically is
> eating up the most RAM.

I think you're running Linux, right?

The "1744168k cached" normally goes in the "Mem:" line, not the "Swap:"
line. And that's the clue to what's using your RAM: Linux uses available
RAM as a variable-size disk cache; the disk cache grows until just about
all of RAM is used. It usually makes sense, the cached data is a copy of
data which is stored on disk, so when an application needs more memory,
the diskcache memory can be freed instantly and allocated to the
application.

Therefore, Linux boxes usually have very little "free" memory.

The "top" utility can sort processes by memory-usage. Also, "ps -vax"
will tell you how much memory each process is using.


> #2. I am consistantly running with 2-300 ports in TIME_WAIT involving port 1984
> 
> # netstat -an | grep TIME | grep 1984 | wc -l
> 253
> 
> Im not sure if this is normal either, nor am I sure if it is bad or
> not?

It's not unusual, and quite harmless. The TIME_WAIT state happens when a
socket is closed; the operating system keeps the socket around for some
time (usually 20-30 secs, cannot remember what the Linux default is) to
make sure that all packets destined for this socket have been received
(there might be some duplicated/retransmitted packets still in transit
when the socket is closed). This makes sure that a new connection using
the same port will not see packets from the old connection.


> Here is the output from some of the "bb" buttons at the top of my
> hobbit page. If anything stands out, any help would be apprieciated.
> 
> DNS statistics:
>  # hostnames resolved  :      138
>  # succesful           :      134
>  # failed              :        4
> DNS lookups completed                    1188421854.099983          9.239654

Your DNS lookups are a bit slow - 9 seconds for 138 DNS lookups. Nothing
critical, just a bit slower than I'd expect. Installing a local caching
DNS daemon is a good way to eliminate this problem.


Regards,
Henrik