[K12OSN] Poor performance woes

Gideon Romm ltsp at symbio-technologies.com
Wed Sep 21 01:01:32 UTC 2011 

Should be NBD_SWAP = True

(it won't understand "on") :)

On Tue, Sep 20, 2011 at 6:51 PM, Jomegat <jomegat at jomegat.com> wrote:
> 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
>>>>>
>>>>> _______________________________________________
>>>>> K12OSN mailing list
>>>>> K12OSN at redhat.com
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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.
>
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