[ale] adding swap? was "that same darn NFS problem SOLVED"

[ChangingLINKS.com]

That is a great idea! My server gets crushed by a program that I call LINKER.
LINKER makes multi-threaded connections to the Internet and collects data. Of 
course, while it is collecting the data, some of the web sites that it 
collects data have connection errors.

I had two programmers look at the software, and it seems to bottleneck at the 
nic card. I can open another session and run as many as 2 more instances of 
the program - but usually the server gets sluggish (insofar as gettting 
results) at 2 instances.

While that is going on, I can open 2 more instances on two more servers, and 
all of them seem to run at full speed - so it doesn't seem to be a data 
transfer problem.

This is why I was adding 2 nics to the server. This is also why I think it may 
be a good idea to double my swap?

How do I run a test to see whether more swap is needed?

I have 512RAM, and 1019 swap(I think).


Drew



On Monday 17 February 2003 1:38 pm, Michael D. Hirsch wrote:
> On Monday 17 February 2003 02:30 pm, Chris Ricker wrote:
> > On Mon, 17 Feb 2003, James P. Kinney III wrote:
> > > With a 2.4.x kernel and RAM <=4G swap=2xRAM
> >
> > That's not necessary. There was a bug in early 2.4.x that required
> > swap=2xRAM for decent performance, but that's long since been fixed...
> >
> > You need enough swap to hold your working set. That could be anything
> > from no swap to gigabytes, depending on what you do on that system....
> 
> Right, but the rational I heard is 
> 
> 1.  Having swap doesn't hurt
> 2.  Unless you have so many processes and so much swap space that you get 
> swap bound
> 3. swap = 2 x RAM is a reasonable heuristic.  If you use much more than 
> that you are probably swap bound, but up to that amount could really 
> happen without getting swap bound.
> 
> Obviously one can create loads that would be usable with more than that 
> much swap in use.  One could also create loads that are unusable with less 
> than that much in use.  It is just a rough guess that often works okay, 
> and few of us have the time or ability to really do an analysis of our 
> swap needs.
> 
> Michael
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> 
> 

-- 
Wishing you Happiness, Joy and Laughter,
Drew Brown
http://www.ChangingLINKS.com
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