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help5507

This forum is provided to promote discussion amongst students enrolled in CITS5507 High Performance Computing.

Please consider offering answers and suggestions to help other students! And if you fix a problem by following a suggestion here, it would be great if other interested students could see a short "Great, fixed it!"  followup message.

How do I ask a good question?
38 articles posted by this ANONYMOUS person
Showing 38 of 148 articles.
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SVG not supported 9:17pm Fri 15th Nov, ANONYMOUS

It seems the project 2 marks have been made available on csmarks. May I know where should the inquiry about the project goes? And what is the average score for the project?


 UWA week 42 (2nd semester, week 12) ↓
SVG not supported 1:49pm Sat 19th Oct, ANONYMOUS

The marks are already on csmarks. But if you are requesting more details, I'd say good luck.


 UWA week 41 (2nd semester, week 11) ↓
SVG not supported 5:59pm Sun 13th Oct, ANONYMOUS

ANONYMOUS wrote Sorry, I meant N 250000.


SVG not supported 5:57pm Sun 13th Oct, ANONYMOUS

Additionally, what should we do if N is so large that we cannot gather the results into a single process? When N is large, even if the original matrix has a low non-zero rate, the resulting matrix is likely to have a non-zero rate close to 1. So for ...


SVG not supported 5:12pm Sun 13th Oct, ANONYMOUS

Given that the project involves working with large values of N, there's a risk of integer overflow if the program doesn't handle numerical limits carefully. I would suggest that fellow students take care to avoid this issue, and the marker should b...


SVG not supported 2:48pm Sun 13th Oct, ANONYMOUS

Thank you for your response; I appreciate it. I didn t expect to see staff available on such a weekend. I believe I have a third option fully generating the operands for all processes while ensuring that the results are consistent across them. This...


SVG not supported 2:32pm Sun 13th Oct, ANONYMOUS

ANONYMOUS wrote This can be done if they follow the same generation sequence.


SVG not supported 2:28pm Sun 13th Oct, ANONYMOUS

If they don't close for us, then I think it will be reasonable for us to start mining ;)


SVG not supported 2:26pm Sun 13th Oct, ANONYMOUS

Or, should we just assume every process shares the same input data, but only does their own parts of computation


SVG not supported 1:42pm Sun 13th Oct, ANONYMOUS

In Project 1, the process was straightforward you generated the operand matrices, and they were shared across all threads. However, in Project 2, we may need to broadcast the operands to different processes, at least partially. Is this what we're ex...


 UWA week 40 (2nd semester, week 10) ↓
SVG not supported 6:30pm Sun 6th Oct, ANONYMOUS

Since Project 2 heavily depends on it, I would appreciate receiving some feedback before I begin work on Project 2.


 UWA week 38 (2nd semester, week 8) ↓
SVG not supported 3:02am Thu 19th Sep, ANONYMOUS

I mentioned in another thread that a multiplication runtime of around 600 seconds is quite reasonable. BTW, I noticed that you are using sbatch which is supposed to be 10 times slower than srun . I have posted about this before, but there is no offi...


SVG not supported 6:11pm Mon 16th Sep, ANONYMOUS

Sorry, the first line of the previous reply is incomplete Your computer may also have pagefile.sys or swapfile enabled, so it is possible that you will not encounter an OOM (Out of Memory) error as it will swap memory between physical memory and disk...


SVG not supported 6:04pm Mon 16th Sep, ANONYMOUS

Your computer may also have pagefile.sys swapfile enabled. https www.man7.org linux man-pages man3 malloc.3.html


SVG not supported 5:33pm Mon 16th Sep, ANONYMOUS

And a reminder if anything is not working as expected, you can use scancel job-id to kill your job so you will not have many jobs stuck in the queue.


SVG not supported 5:26pm Mon 16th Sep, ANONYMOUS

You can use squeue -u USER to get all of your currently running job, and then use sstat -j job-id to show the details of your job, including an entry representing memory usage. It's important to note that simply allocating memory via malloc() ...


SVG not supported 12:51pm Mon 16th Sep, ANONYMOUS

I believe a proper implementation should be able to perform the multiplication for p 0.05 and N 100,000 in under ten minutes. In fact, ten minutes is a generous estimate, and your program will likely complete the task in less time.


SVG not supported 12:48pm Mon 16th Sep, ANONYMOUS

Yeah I agree with the one above. I fixed core to 28 and got a perfect U shape by setting different thread numbers.


 UWA week 37 (2nd semester, week 7) ↓
SVG not supported 1:17pm Sun 15th Sep, ANONYMOUS

Cannot find any related entry on cssubmit https secure.csse.uwa.edu.au run cssubmit


SVG not supported 12:14pm Sun 15th Sep, ANONYMOUS

I agree. It might work in later versions, but earlier versions of OpenMP could exhibit undefined behavior. In this case, I think we might just need to choose the option that makes the most sense.


SVG not supported 12:12pm Sun 15th Sep, ANONYMOUS

Yeah I was also using runtime to experiment with different scheduling and chunk sizes.


SVG not supported 12:11pm Sun 15th Sep, ANONYMOUS

I wrote two separate functions. One generates the compressed form directly, without relying on an existing X; The other generates the compressed form from an existing X. I hope this covers what they're asking for, as at least one of these approaches s...


SVG not supported 3:50pm Thu 12th Sep, ANONYMOUS

OpenMP offers five scheduling schemes for the pragma omp parallel for directive. However, out of these, only static , dynamic , and guided are the real deal when it comes to scheduling. The other two, runtime and auto , aren t true scheduli...


 UWA week 36 (2nd semester, mid-semester break) ↓
SVG not supported 5:57pm Fri 6th Sep, ANONYMOUS

sorry, use this link https en.cppreference.com w c numeric random rand


SVG not supported 5:53pm Fri 6th Sep, ANONYMOUS

A minimal test case to show the performance difference. openmp 101.c c include inttypes.h include limits.h include omp.h include stdint.h include stdio.h include stdlib.h int main() printf("omp get max threads() u n", omp get max ...


SVG not supported 5:19pm Fri 6th Sep, ANONYMOUS

Moreover I have never tried to use sbatch before because I thought running a program with srun should have identical or at least similar performance. For example, if I were you I would run openmp 101-b.sh as bash cc -fopenmp -o openmp 101 . op...


SVG not supported 5:03pm Fri 6th Sep, ANONYMOUS

First I would like to point out that your code may have undefined behavior. int i and long loops have different data type, and loops have value equal to 10000000000 which is greater than INT MAX, so the loop should never finish. But since the beh...


SVG not supported 8:18pm Thu 5th Sep, ANONYMOUS

In addition to my previous response, I realize that it may be impossible to perfectly time a multi-threaded function. Although clock gettime(CLOCK THREAD CPUTIME ID, t) excludes scheduling delays, we will always call the function in the master thre...


SVG not supported 8:00pm Thu 5th Sep, ANONYMOUS

You can always set the memory limit in the parameters, like --mem 60g .


SVG not supported 6:32pm Thu 5th Sep, ANONYMOUS

Using --cpus-per-task 128 is the correct way to specify the thread count. Since we don not have control over how Setonix operates, we must work with its scheduling behavior as best we can. I still cannot see the C code, so I am not sure how you meas...


SVG not supported 6:22pm Thu 5th Sep, ANONYMOUS

I just assumed that all matrices are square and defined a constant N for both rows and columns. I hope our UC does not impose a strict limit on this. After all, these are just minor details; the main focus of the project should be on the parallel alg...


SVG not supported 2:24pm Wed 4th Sep, ANONYMOUS

I don't expect this to be answered within the week. The funny thing is, the deadline for our lab report is next Friday, which falls in the same week as numerous mid-semester tests. Alas, best wishes to everyone.


SVG not supported 2:11pm Wed 4th Sep, ANONYMOUS

SYSTEM WARNING YOUR STUDENT NUMBER HAS BEEN RECORDED FOR NOT BEING RESPECTFUL TO TEACHING STAFF. YOUR INTERNET BROWSER HISTORY IS NOW BEING REVIEWED FOR FURTHER EVIDENCE OF INAPPROPRIATE BEHAVIOR. Just kidding. I agree with you mate.


SVG not supported 11:38pm Tue 3rd Sep, ANONYMOUS

Moreover, RAM is not a concern here, only the time matters.


SVG not supported 11:36pm Tue 3rd Sep, ANONYMOUS

I only check the result if N 10,000 . 100,000 3 is an enormous number, even for Setonix. The computation for the compressed matrix is feasible only because we reduce it by a factor of p 2 , where p is 0.01, 0.02, or 0.05. I doubt any...


SVG not supported 11:24pm Tue 3rd Sep, ANONYMOUS

Do you mind sharing the code? I don't think people will give helpful answers without knowing the details.


 UWA week 35 (2nd semester, week 6) ↓
SVG not supported 11:42am Sat 31st Aug, ANONYMOUS

I would say for N 100000 , it is more efficient to store the result in an uncompressed form. When N is large, even if the original matrix has a low non-zero rate, the resulting matrix is likely to have a non-zero rate close to 1 .


SVG not supported 10:36am Fri 30th Aug, ANONYMOUS

Hi Professor, If we have a matrix A with N rows and N columns, we can compress it into two new matrices, AX and AY , each with N rows and M columns. The problem is, we don t know what M is when allocating memory for ...

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