[K12OSN] Relative performance characteristics

["Terrell Prudé Jr."]

Sounds like your issue is DRAM.  Depending on the apps running (e. g.
TuxType), it could also be server bandwidth, but from what you describe,
it sounds like you're starting to swap to disk once you hit 60 clients. 
That will definitely slow any kind of terminal server, including LTSP
servers, to a crawl.  You might not have any DRAM hogs, but if you've
got a bunch of instances of an app running, all using a certain amount
of DRAM, that adds up.  For that reason, I normally didn't push my
servers, which generally have 4GB DRAM, past 30 clients.  Since you're
only at 65% CPU usage, it really doesn't sound like that's your
problem.  Also, make sure that you are indeed checking that *all* of
your server's CPUs are seeing only 65% usage.  By default, top shows
only an average between all of them.

--TP
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Immanuel Derks wrote:
> Hi all,
>
> Just wondering at the moment how people feel about the difference in
> performance characteristics between the latest Xeon core duo breed
> processors and the old fashioned dual Xeon server layouts for LTSP.
>
> We have multiple IBM X235/x236 with double Xeon 3GHz processors
> outfitted for a failover LTPS configuration at our school (80-100
> clients) and are wondering whether we can simplify the configuration by
> making use of a single server with double Xeon dual core processors (say
> an X3650 that comes with 2 dual-core Xeon 2.33/2.66 or 3.0GHz)
>
> Can anybody testify a configuration with similar loads who made such a
> swap? I know dual core processors don't have a similar performance as 2
> separate xeons at the same speed, but one might wonder with all the
> threaded apps en memory use in LTSP, that it could stack up to it...
>
> I must say I feel a bit skeptical sometimes at the performances quotas
> that I sometimes see here on the list, since we noticed (even on our
> glass backbone) that x236 servers with 3GHz processors and 8GB ram
> fitted are really dropping performance to a slow when 60 people login (2
> classes) and start working on office and firefox stuff at the same time.
> That's why we needed 2 similar servers and we are doing fine now.
> As soon as the CPU loads get over the 65% peak loads, we get a real drop
> in performance, but no iowait or memory hogs or anything....
> (we basically run standard RedHat 4 edu edition)
>
> Kind regards,
>
> Immanuel Derks
>
>
>
>
>   
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