[sf-lug] GNU Denemo chokes a dual core 2 GB server at the school
jim at well.com
Mon Sep 24 16:59:03 PDT 2007
here's how i understand attacking the problem:
* watch network traffic to see if the network is overloaded.
* watch workstations/chubby-clients to see where the CPU is working
* watch the server to see where the CPU is working
On Sep 24, 2007, at 4:09 PM, Christian Einfeldt wrote:
> Here is the next issue for our public middle school project. And it
> is actually part of a recurring theme, it seems: why is our linux lab
> lagging, when most people think that it should be able to handle what
> we are throwing at it. My question is fairly long to explain, but
> simple to summarize: why are we experiencing delays in playing music
> compositions using GNU Denemo under Edubuntu over a GB network that
> should be performing better, and what can we do to solve the problem
> without spending any money?
> As most of you know from reading this list, I am a volunteer
> supporting a public middle school with FOSS. We have a brand new dual
> core server with 2 GB of RAM whose only purpose in life is to support
> 24 chubby clients running edubuntu. The thin clients have at least
> 256 MB of RAM, and most of them have swap space on their hard drive
> also, although some of them are true thin clients in that the hd has
> no swap and is basically a vestige. I am told that we have a gigabyte
> network. The server feeds the signal to the first 18 clients through
> one GB switch, and then that switch feeds another identical switch
> with services about 6 more clients.
> Our problem is that when we use GNU Denemo to play the short little
> compositions that the students write in class, we can have only one
> student play his / her composition at a time or the system is choked,
> meaning that it lags. More specifically, all of the students find
> that their GNOME desktops are almost completely non-responsive to the
> mouse. The mouse still moves, but programs launch very slowly for
> about 5 mins, at which time the choke point is presumably cleared, and
> then one student can again play his / her composition. It might be
> possible for, say, 2 students or maybe even three students to play
> their music; but we don't know where that stress point is.
> And, in some ways, it doesn't even make sense to slowly add students
> and have them play music, simply because some people who have heard of
> this problem in passing furrow their brow and say that we shouldn't be
> having these problems.
> We are, of course, going to be trying to get more RAM in the clients;
> and swap for all of the clients; and we have thought of running GNU
> Denomo natively on each of the clients by booting them as stand alone
> work stations.
> For those of you who are familiar with the school, you can stop
> reading here, because what follows is basic data about the school, and
> you probably don't need to read it again.
> This inner city school has absolutely no budget for a real tech
> support person, and all of the teachers already are at work by 6:50
> a.m., and they usually stay until 6:30 p.m., and then each of the
> teachers is expected to be available to field phone calls at home
> until 8 p.m. All of this might sound kind of drastic, but our
> students typically come to this school of 290 students
> under-performing their grade level by 2 grade levels, but leave the
> school as 8th graders typically performing at or above grade level.
> Seventy-five (75%) of our students come from households below the
> federal poverty guidelines. 65% of our students are African American;
> 17% are Latino; 10% are Asian; and 8% are Caucasian. Despite the life
> challenges facing our students, last year our students tested in first
> place (as a student body) based on standardized testing. So this
> school is succeeding in many ways, but they are really struggling in
> terms of technology, and that is all because of funding shortfalls.
> Coincidentally, the students spend no time here on Windows boxes,
> except for occasionally random Internet browsing on a teacher's
> Windows box. But that is the exception, because, as you can imagine,
> the teachers don't want the students accessing their computers. So
> when the students are not in the lab, they are using PClinuxOS boxes
> in several of the classrooms to do their Internet research.
> Overall, this school is making miracles with no funding. I am hoping
> to move the whole school to FOSS eventually, but of course there is
> still a lot of work to be done. Thus far, the music teacher is fairly
> impressed with the ability of students to compose music on GNU Denemo,
> but she would just like to be able to have all of the students listen
> to their compositions at the same time. Typically, these compositions
> are no more than, say, 6 or 10 bars long, just enough to get the
> students familiar with the basics of scales, rests, note duration,
> tempo, beat, etc. Just the basics.
> Thanks in advance for the help.
> Christian Einfeldt,
> Producer, The Digital Tipping
> sf-lug mailing list
> sf-lug at linuxmafia.com
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