slow down (swapping) on a GS1280 with lot of free memory

[Peter Quodling]

Joerg,


The way I read your responses, it appears you don't appear to be willing to follow the instructions of the support engineer working on your problem. While forums like this may provide some additional knowledge, that person is the absolute expert in the area, and will be asking you things that are relevant to the problem. Questioning/Challenging his/her responses in a forum like this (or on a web page) doesn't add to the solution.

I am also intrigued by your comment about not wanting to devote a couple of disks to the problem, (MAy 11 18:37) If I had a GS1280 that wasn't functioning as expected, I would be trying each and every suggestion of the support people, rather than arguing the esoterics of NUMA. (I'd do it for an ES47 that was playing up...) the relative cost of interim use of a couple of disks versus desired functionality of a GS1280, is chalk and cheese to me.

I am sure that the support person working on this was had to move heaven and earth to get a GS1280 to replicate your problem - they don't grow on trees, even inside HP - All I have seen in your posting is a small sample program that creates a symptom - more information about configuration, the real client application that is causing this problem (not just an example piece of code), would all do better to getting a real solution to the problem.

I also noticed that you are assigning 0 and 1 points for the detailed responses that you are getting - you may care to consult the tips for the ITRC forum - while your problem may not be resolved, the likes of Hein,alexey and Florian are going well out of their way to assist, and a 0/1 point value is really a slap in the face, for their efforts, advice (including hein tracking down people for status ) If you are looking for help here, show a touch more appreciation for the efforts.
The Tips are at http://forums1.itrc.hp.com/service/forums/helptips.do?#33


Peter.

[Joerg Schulenburg]

@Peter: I am willing to follow instruction, if
they make sence. It is simple to answer to my questions in the way "just try this, it may help", but it costs to do so and that without
solving the problem.
Our machine cost about 1Million dollar and some thousand a year for support. After 6 years we can through away the machine.
So every day cost us about 406$ only for the hardware as a linear approximation.
Every job is running about 30days on that machine. A reboot does destroy statisticaly 15days scientific work on that machine, which is about 6090$ per crash and reboot.
This is only an approximation. I get money
to admin that machine in a way that the number of reboots
and crashs are minimized.
So I have to value each reboot, thats my job.
If you read my story, you will see that
the cause for the trouble is a bug in the kernel or bad implementation or what ever
you call it. So I think its HPs turn to help.
My impression was, that whether the support was able to follow my conlusions or they
followed and were unwilling to ask engeneering (that hase hopefully changed now).
So I had to spend much of my time
to learn lot about paging and swapping
to have enough arguments for the support to change their mind (successfull?).
I asked lot of questions and got only few answers back, no details, which would help
to understand Tru64s VM and NUMA.
I am not what you probably call an expert, but I am able to think, able to draw conclusions. And until now nobody of the experts was able to show me that I am on the wrong way.

>>I am sure that the support person working on this was had to move heaven and earth to get a GS1280 to replicate your problem

Do they? What I got as information by email
was: "Our engineering did some tests with your reproducer on our testsystem and found some problems. Problems are solved by changes on the kernel. Further tests were successfull. ..." (translated from german to english).
No information what system they use, which problems arise. Did they reproduce my results
or do they got some other?
Weeks (or months?) ago I told the support to get a login on our machine to see what happens, but nobody was asking for! Support seems not interested in it.

The patch I got seems to improve situation on the GS1280, but I still not know is it because the problem is solved or do they found a workaround which triggers other problems.

>> arguing the esoterics of NUMA

If the support tells you, that an (non-numa-aware) application
can only use 1/32 of the overall memory
on a HP-NUMA without swapping and there is no need for support, you have to arguing!
That statement has made me very angry and I now understand why people is saying that
HP does not play a role in the HPC (High Performance) world.
By the way the person who did
tell me that stupid statement was also mentioned to be an expert *sigh*.

>>noticed that you are assigning 0 and 1 points for the detailed responses

Sorry, that I am so severe (right word?), but
answers did not helped me. Other users having the same problem and searching for it within this forum can spare time (and reboots) if they ignore 0pt answers, regardless if answers came from experts or not.
Be sure that I value answers which really help. And also I have efforts making explanations and suggestions here, having the hope that they will be read and finaly solve
the problem.

Trying to make this world better ...

[Joerg Schulenburg]

I have some news on the above mentioned webpage. Seems that ubc plays an important role for swapping, because borrowed ubc pages
can not be stolen by other RADs.
Comments are welcome.