[K12OSN] Poor performance woes

Tue Sep 20 21:02:36 UTC 2011

That just tells you the service is on. If you don't have NBD_SWAP in
your lts.conf, then you are not using it.

I believe there is also a parameter to use local swap from a hard
drive, though I don't recall. Perhaps check the docs. Otherwise, if I
remember, I will look in the code.

-Gadi

On Tue, Sep 20, 2011 at 4:51 PM, Jomegat <jomegat at jomegat.com> wrote:
> On 09/20/2011 04:36 PM, Gideon Romm wrote:
>>
>> Try enabling NBD_SWAP.  If the clients have insufficient RAM, the best
>> you can do is add swap space and hope the OS will swap out something
>> else.
>
> Thanks.  I've already got that enabled as best I can tell.  Here's a snippet
> from chkconfig --list:
>
> xinetd based services:
>  [snip]
>        nbdrootd:       on
>        nbdswapd:       on
>
> Maybe that's where the 21MiB/sec is coming from.
>
> As soon as I can get back to the school, I'll run top on the TC and see
> what's going on.
>
> Would it be possible (or advisable) to run swap on the TC from a local HD
> instead of over the network?
>
>>
>> -Gadi
>>
>> On Tue, Sep 20, 2011 at 3:18 PM, Jomegat<jomegat at jomegat.com>  wrote:
>>>
>>> I have a K12Linux setup based on EL6-64.  The TC's are ancient i686's
>>> with
>>> 256M RAM and 10/100 nics.  The TS has a gigE NIC, and between the TS&
>>>  TCs
>>> is a managed switch with 2 gigE ports and 24 10/100 ports.  The TS is
>>> connected via one of the gigE's.
>>>
>>> We have a student who is having real performance problems when he loads a
>>> page.  I went in today to be there while he was experiencing woe, and ran
>>> the system monitor applet.
>>>
>>> When he loads the web page - with no flash in it that I can find - the
>>> network maxes out at 12MiB/sec, and it takes an eternity for the page to
>>> load.  He reports that sometimes this particular page will cause the TC
>>> to
>>> crash (black screen with text followed by login screen), but he was not
>>> able
>>> to reproduce that while I was there.  I suspect there is some user error
>>> involved in the crash scenario, but it will be difficult to prove.
>>>
>>> I had tried running firefox as a local app last month, but the school
>>> needs
>>> flash, and it requires 512M.  Performance on these TC's was substantially
>>> worse when running FF as a local app, so I backed off of that.
>>>
>>> The page he was trying to load is password protected, but I had him
>>> ctrl-U
>>> while he had it open, and save the source to a file which I can share if
>>> need be.  It is filled with javascript, but I'm not sure that's the
>>> culprit
>>> (though it seems the most likely suspect).  I found no .flv, FLV, .swf,
>>> or
>>> .SWF in the file anywhere.
>>>
>>> As an experiment, I connected a monitor, keybd, and mouse directly to the
>>> server and had him login there.  The page loads just fine that way.  That
>>> might be a possible solution, but for some reason, the display is
>>> incredibly
>>> blurry.  If I make that permanent, I'd have to run some cable through the
>>> wall (they're pinched in the door right now, and barely reach).
>>>
>>> Before they called me in to look at this, he had been bringing his mom's
>>> laptop to school so he could do his work (it's an online course).  If it
>>> crashes while he is taking a quiz, he loses a test attempt or gets a bad
>>> grade, so this has to be reliable.
>>>
>>> His mom is on the school board, and she is pushing the school to abandon
>>> LTSP in favor of a Windows solution.  They think that if they install
>>> some
>>> flavor of windows on the TC's they will get better performance, but I
>>> believe they won't, as flash will need 512M no matter the OS.  I think
>>> they
>>> will need all new PC's if they go that route.
>>>
>>> I am on the cusp of losing my network to Windows, at which point I will
>>> resign my post as unpaid volunteer sysadmin, so if I sound a little
>>> desperate, now you know why.
>>>
>>> Any help here would be greatly appreciated.
>>>
>>> --
>>> Jim Thomas            Principal Applications Engineer  Bittware, Inc
>>> jthomas at bittware.com  http://www.bittware.com    (603) 226-0404 x536
>>> The problem with the future is that it keeps turning into the present -
>>> Hobbes
>>>
>>> _______________________________________________
>>> K12OSN mailing list
>>> K12OSN at redhat.com
>>> https://www.redhat.com/mailman/listinfo/k12osn
>>> For more info see<http://www.k12os.org>
>>>
>>
>> _______________________________________________
>> K12OSN mailing list
>> K12OSN at redhat.com
>> https://www.redhat.com/mailman/listinfo/k12osn
>> For more info see<http://www.k12os.org>
>>
>
>
> --
> Jim Thomas            Principal Applications Engineer  Bittware, Inc
> jthomas at bittware.com  http://www.bittware.com    (603) 226-0404 x536
> The problem with the future is that it keeps turning into the present -
> Hobbes
>
> _______________________________________________
> K12OSN mailing list
> K12OSN at redhat.com
> https://www.redhat.com/mailman/listinfo/k12osn
> For more info see <http://www.k12os.org>
>