I hope the list is being archived and folks can search the archives! We should include the link to the archives in the introductory email. -Kumar

On May 4, 2016, at 3:08 PM, Allen, Benjamin S. <[email protected]> wrote:

Hi Fabien,

Answered in-line below:

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For those of you who dont know me, I am Fabien Delalondre from EPFL working on brain simulation in Switzerland. I have just got access to knl00 as part of the ALCF Early Science Program. I have a few questions related to KNL00. I apologize already if they sound like silly questions ... Appreciate all the help I can get ...

0) Is there any wiki accessible where users would add interesting facts/experience/general documentation etc ?

Nothing setup, but we could if there's interest from the group.

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1) What is the recommended placeholder for the files to be written to ? Should I use home ? What is the file system/expected bandwidth on this file system

Use the local SSD for any temp files. This is just a Intel DC S3710 SATA 200GB. /home is fine, but don't expect it to be fast, nor rely on it for any I/O sensitive work.

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2) Is there a possibility to change the card configuration from user space ? Or should I use [email protected] mailing list every time I want to ask a different configuration ?

Assume when you say card you're referring to the KNL system itself, and I'm assuming when you say configuration you're asking about MCDRAM's mode and model. If so yes this is possible if needed. It requires BIOS changes, but we have a utility to change those settings in Linux. Changes are applied on reboot.

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3) When the /soft/scheduling/knl/knl.txt​ text says knl00 node status: in use by William Scullin until 11:30 am CT 4 May 2016 - e-mail to to preempt running benchmark​. Can I still use the system or is there a policy defined ? How can I "reserve" the KNL ? Should I send an email to the mailing list ? With the time difference between the US and Chicago I could use it every night in Chicago :-)

No you cannot use the system if someone has listed that they're using it in that file. You can of course email this list asking to preempt whoever using it if you think you need to. For reservations just add text to the bottom of the same file stating the reservation date, start and end times.

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4) I understand there is no scheduler on this system up to now. Please let me know if this is not correct.

Correct no scheduler.

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5) Can you point me to someone who has lots of experience with VTune on KNL ? Vitali was mentioning to me it does not produce the results he expected. I d like to know more about this. Any other profiling tool you would recommend ? Any documentation available on performance counters available ?

We still don't have access to Vtune 2016's special KNL add-on, so we're a bit out of luck so far. As Kevin said, we're at the forefront of KNL knowledge. Unsure if Advisor is any better.

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6) Is there a debugger available on this node ? If the answer is yes, which one ? Can I use run a vnc server to connect and improve response time of the graphical interfaces ?

No VNC. Use X11 forwarding.

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7) Is memkind/autoHBM installed on the system (http://www.nersc.gov/users/computational-systems/cori/application-porting-an... Any recommendation regarding using or not using them ?

Yea they're installed.

Ben Allen

HPC Systems Administrator ALCF Operations - Joint Laboratory for Systems Evaluation Argonne National Laboratory Email: [email protected] Office: (630) 252-0554

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