[K12OSN] Poor performance woes

Tue Sep 20 22:51:50 UTC 2011

On 09/20/2011 05:02 PM, Gideon Romm wrote:
> 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.

OK, there was nothing of the sort in lts.conf.  I added this line:
NBD_SWAP=on

I'll test it when I can get over there.

Thanks a million.

>
> 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
>>>>
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>>>>
>>>
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>>
>>
>> --
>> 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>
>>
>
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-- 
Jim Thomas            jomegat at jomegat.com
  "And" is a word that should never be used at the beginning of a sentence.