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We have added 5-minute queues in the 8, 16, and 32 PE sizes. The goal is to help users in the development phase who, given the current load on ARSC's T3D, often find their debugging jobs queued up behind one or more 24-hour jobs.
We have also increased the priority of the 32 PE queues which have been blocked for days at a time by 8 and 16 PE jobs. The reasoning parallels that used when we gave the 64 PE queues the highest priority (see Newsletter #95). With a busy machine, the likelihood of a contiguous block of 64 or 32 PEs opening up when the 8 & 16 PE jobs get to jump in first, is pretty low.
We have also rewritten the queue ethic which attempts to define fair play amongst the T3D users. In this version, we give ARSC staff the right to enforce the policy. Don't worry, this is not a philosophical shift: we will deal with situations as usual, by contacting people by email and phone. The two purposes for this are to stress the importance of the rules and to cover ourselves in some extreme case. The only scenario I can think of in which we would actually hold a job is if someone submitted too many jobs (by mistake or through ignorance of the ethic) and then became unreachable. There hasn't been a single case when a T3D user didn't respond immediately when informed that they were violating the ethic.
The new ethic has three rules (see below). The first is simply a restatement of the old ethic. The second will ensure that a single user can't take over 75% of the T3D at a time by running jobs of all different sizes. The third is a cautious approach to the new 5 minute queues.
As always...
Feedback on our queue structure and management is always appreciated, and contributed greatly to the current set of changes. After a couple of weeks, these changes to the structure and ethic may be up for review.
Here is the official notice of the changes (on denali, "news t3dbatch"):
---------------------------------------------------------------------
T3D Batch Queues
================
The T3D batch queues were changed on Nov. 19, 1996. The current T3D
queues (in priority order) are:
Name of queue Number Maximum jobs Time limit When queue is
of PEs per queue on queue enabled
m_64pe_10m 64 1 10 minutes always
m_64pe_24h 64 1 24 hours always
m_32pe_5m 32 1 5 minutes always
m_32pe_24h 32 1 24 hours always
m_8pe_5m 8 1 5 minutes always
m_16pe_5m 16 1 5 minutes always
m_8pe_24h 8 2 24 hours always
m_16pe_24h 16 2 24 hours always
m_128pe_5m 128 1 5 minutes Fri 6PM to Sun 4AM
and after downtimes
m_128pe_8h 128 1 8 hours Fri 6PM to Sun 4AM
A request made to these queues will be run as soon as enough PEs are
available to satisfy the request. T3D jobs run to completion without
interruption.
Specifying Queues
=================
When submitting a job to the T3D, you do not name one of the above
queues. Specify only the MPP pipe queue:
#QSUB -q mpp
Based on the number of PEs and time you request, NQS will route your
job to the smallest/shortest possible queue. For complete
documentation of NQS, including examples, see:
http://www.arsc.edu/support/howtos/usingnqs.html
Queue Ethics
============
The T3D is a popular, limited resource. ARSC has found that T3D
users are willing to work together to provide fair access to the
queues. Please follow these 'rules':
1) Submit/execute no more than one job per 8 or 24 hour queue at a
time.
2) Do not submit/execute jobs in more than two different 24 hour
queues at the same time.
3) Submit/execute no more than two jobs per 5 or 10 minute queue
at a time.
As an example of the "queue ethic," if user "goodman" submitted a
job to the m_64pe_24h queue, he/she would not submit another until
the first had run to completion and thus made the queue available to
other users. Meanwhile, "goodman" could have one job in the
m_32pe_24h queue as well, without violating the ethic. He/she could
not have one in each of the m_32pe_24h and m_8pe_24h queues as well,
however.
Please contact 
(consult@arsc.edu or 907-450-8602) if
you feel that the queues are being misused, and we will work to
resolve the situation. ARSC may hold or delete jobs that are
submitted in violation of the 'rules' outlined above.
User's UDBSEE Limits
====================
Most T3D users currently have a limit of 128 PEs for batch access
and 8 PEs for interactive access. Users can check their limits with
the udbsee command:
udbsee | grep jpelimit
The output will indicate your limits in interactive(i) and
batch(b). For example:
jpelimit[b] :128:
jpelimit[i] :8:
If your batch PE limit is too small to access the NQS queues and you
would like to use them, please contact User Services.
Tracking Your Jobs
==================
Users can query the NQS batch system with the command:
qstat -a
to see what NQS T3D jobs are scheduled to run on the T3D. The
utility mppview is available to see what jobs are currently running
on the T3D.
-- Tom Baring, Nov. 20, 1996
A: {{ Do programmers get carpal tunnel syndrome? How bad is it? Can you
avoid it? }}
Carpal tunnel syndrome is for everyone. My sense is that this is one
of those injuries that provides plenty of east-to-ignore warning
signs, and that can really mess up your life. I personally know two
people who have lost good careers in graphic design and programming
due to CTS (not to mention losing hobbies, sports, etc.). Here is a
Web site devoted to typing injuries:
http://www.cs.princeton.edu/~dwallach/tifaq/
Thanks to the reader who sent this in:
> Yes, it is a repetitive motion injury. It is painful and I have lost
> strength in my hands. Doing simple things causes pain and aggravates
> the injury, like holding a book to read it, holding a steering wheel
> when driving, using a knife to cut something, writing with a pen or
> pencil.
>
> To try to avoid it, use ergonomic workstations (chairs with
> adjustable arms, adjustable keyboard drawers with a soft
> wrist-rest). Be aware of your hand positions and try to keep them
> neutral (not bent at the wrist). Take frequent breaks (at least
> every 45 minutes) to do something else briefly.
>
> Once you have it, I've found physical therapy (ultra-sound, massage,
> icing down the area, and strengthing and flexibility exercises) helps
> a lot. The wrist-braces you see everyone wear help some. I've heard
> that the software which allows a combination of voice commands and
> keyboard usage helps some (but the technology still needs some
> work).
Q: If you expect to create core or mppcore files, how can you arrange
for them to be removed automatically, so they never use up quota
in the current directory?
[ Answers, questions, and tips graciously accepted. ]
Contact:
Thomas J. Baring ARSC Web Specialist ph: 907-450-8619 Donald Bahls ARSC User Consultant ph: 907-450-8674 Arctic Region Supercomputing Center University of Alaska Fairbanks PO Box 756020 Fairbanks AK 99775-6020
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