Préallouée VI environment in paralleled for loop

Similar Questions

• parallel for loops does not

  Hello.

  I'm learning the multi - thread programming. To start, I use "parallel for loops" and I was surprised that it does not work. One - thread loop work a few times faster (depending on settings) that multi - thread. I don't know why, and it is my request to correct my Vi to work properly.

  Lenovo, G580, Windows 7, 64-bit computer

  Intel Core i7 3632QM
  Ivy Bridge
  Specification Intel (r) Core i7-3632QM CPU @ 2.20 GHz
  Package (platform ID) Socket 988 B rPGA (0x4)
  Number of hearts 4
  Number of threads 8

  LabView 2011.

  Altenbach says:
  

  Gibbon wrote:

  What was 'strange' behavior?  In "linia dluga" when inside the loop is on '1' of the "spreed up' between one and multi-fil is about 3 times, when I put it in '20' this grow to 6.2. It was strange form me, becourse I expect a similar value.

  A parallel FOR loop has an overhead for parallelization (split the problem, then go back the results, etc.). If the code is very fast, the overhead is proportionally larger. If the Subvi takes a long time to complete, the overhead of parallelization is insignificant. It is often not worthwhile to parallelize the loops with a very simple and fast code.

  Gibbon wrote:

  Altenbach - I have another question if you can help me - how did you "seconds relative high resolution." VI "? -I want to say how did you know that there is this 'vi '. And thanks a lot for your modyfications.

  You can find it in vi.lib\utilities. It is well known.

  Maybe not well known enough!  the 'Hidden gems' package adds to your palattes.  It has also been considered by a nugget of the community

• LabVIEW parallel for loop and OpenMP

  Hello:

  It's just a curious post, I just learned about OpenMP and I found that OpenMP helps you to parallelize loops in c about the same way that you can use the loop For parallel in LabVIEW.

  The loop For Parallel LabVIEW is being implemented under the hood using OpenMP? Or is it just a coincidence?

  No, it is not implemented LabVIEW parallel for loop under the hood using OpenMP. You might be interested to read this article on modern developments in the LabVIEW compiler architecture. Specifically, in this case, it's the DFIR technology discussed here that facilitates parallel for loop transformations.

• Parallel for loop 2D table

  Hello

  I don't have any experience with parallel for loops, so I need your help.

  Goal: To do a calculation (average, average) on the rows (or columns) table 2D as quickly as possible. The calculations are independent of each other and I would get a table 1 d with the results.

  I read a few posts on parallel for loops and I would like to find an example for my trivial problem, but I can't.

  Could you help me, it is possible is improve it the effectiveness of the calculation on lines with parallelism in LabVIEW? and it is, could you post an example how to do?

  Thank you

  If the speed issues, do not write your own "average." First of all, it already is in the range of statistics, but then you must be inline your average VI or do the calculation explicitly (as shown below). the size of the array never changes for the duration of the loop, it seems redundant to get the size of the array on each iteration.

  Here's what you could do.

  

  On my bench, it's much faster than the use of 'mean.vi' of the palette. Average a overhead, Subvi (1) (2) needs to get N with each call and (3) is also an unnecessary error checking.

  (Sorry, I have 32 processors, so the number of instances is set a little high. Modify if needed).

• How to create parallel tasks using parallel for loops

  Hello

  I'm going to put in place a program that communicates with the six logical controllers and must read the status of the system every 100 Ms. we use OPC datasockets for this, and they appear a bit slow.

  I created a uniform method of comm. for all controllers, and now I find myself this method of programming six times to communicate with each system. I was wondering if it could be done more elegant using the parallel for loop, in which case I program an Exchange once and then six workers running simultaneously. Since a picture is clearer than a thousand words, what I'm asking is:

  Is it possible to replace something like

  

  by

  

  and that for performing these tasks in parallel loop (on different cores / in different threads)?

  I have configured the loop to create instances of the 8 to the compilation, so I would 2 surplus available when running instances if I find that I need an additional system.

  The benefits of the Show method in the second photo for me are:

  * takes less space

  * changes need be made only once

  * less blocks, son and other things makes it clearer what is happening.

  * flexibility of the actual number of tasks running (8 available runtime instances)

  * If multiple tasks are necessary, I need only update the maximum number of instances and recompile, i.e. no cutting and pasting necessary.

  Unfortunately, I don't have these available system yet, so there is no way to test this. Yet, I would like to know if the above works as I hope - unfortunately the help of labview is not quite clear to me on that.

  Best regards

  Frans

  Frans, the parallel for loop will work as expected in this situation. The six tasks will run simultaneously in different threads. What part of the aid could be made clearer?

• Waiting for timeouts in parallel for loop

  Hello

  I am currently working on a project where I communicate with a number of devices over TCP. This happens at the same time, which is not a problem as long as does not change the number of devices. Now, I want to open my project to support the case with different numbers of hardware devices, which I want to make a loop (read the device of DB information in an array and iterate over all items).

  I read on a single loop parallel execution for, but it seems that the logical cores is a limiting factor for the number of alternative treatments. Unfortunately, I must also take into account delays in communication which translates as the waiting time for each iteration of the loop.

  As you can see I have this creates a lot of idle time that adds up quickly (running with 10 carrots 4 logic devices takes three times the delay to finish without the loop it would not delay time as all connections are pending at the same time.

  I hope someone can direct me to a solution.

  Thank you

  Move the reference VI opened in the first LOOP.

  You use the same reference for all instances.  So wait for asynchronous call will just see one of them finished and the results.  By placing the reference VI open inside your loop, you will have a different reference for each call of your VI.

• parallel processing: for loop taking place

  Hallo,

  I have a loop 'for' runnin on this system: LabVIEW2009, windows7, intel i7.

  I wonder if and how I can tell to LabVIEW that he would be allowed to run different iterations of the loop at the same time (concurrently) on my processor with 8 cores.

  Now, it will execute the next iteration when it ended the previous, even one so is there no dependencies in iterations.

  I want to give a 'ownership' of the loop, which means that it can be "unfolded" for parallel execution.

  Thank you

  Pier

  pop up on for loop and select "configure interation Prallelism."

  Activate it.

  Wire a certain number to the new 'P' of entry to specify how many processors to spread it everywhere.

  Ben

• How to know the degree of optimal parallelism for my database?

  I have an important application on my (Oracle 10,2,0) databae and the box has 4 CPU. All tables are not partitioned. Should I set the parallel degree by myself?
  
  How to know the degree of optimal parallelism for my database?

  As far as I am concerned there is no optimum degree of parallelism at the database level. The optimal value depends on the query based on the plan in use. This may change over time.

  It is not so difficult to abuse of the PQO and end up harming the overall database performance. PQO is a brute force methodology and should be applied with caution. Otherwise, you end up with results inconsisten.

  You can let Oracle manage, or you can manage it on the level of education through advice. I do not have to specify the degrees of parallelism to the object level. As I said, no two queries are exactly alike and what is right for a query on a table cannot be good for another query on the table.

  In the case of doubt put in place the system to let Oracle manage. If you ask really, it's how many sessions to allocate PQO then look at your reports Statspack or AWR and judge your system load. Monitor v$ px_session and v$ pq_slave to see how these views show activity.

  IMHO - Mark D Powell-

• For loop within a while loop

  I have for loop within a while loop... admission to the for loop N comes from the VI selection... the while loop I a condition essentially statement it stops just after to finish all the iteration in loop...

  Entrance to the N loop is bascially driven by a local variable... that's the problem Iam having:

  When I press the Start button to run the program... regardless of the output of the select VI is gives the N of the for loop, then the loop starts and then ends in place... and when the output of the select statement takes a different value (the N of the loop for) loop not work until I restart the program again... What can I do so that the for loop runs again for another value of N, the RUN program button is enabled.

  1. clean your diagram.  Style guides suggest keep the pattern of a single screen.  With a little effort, I was able to get your DB less than 1600 x 1000 pixels.

  2 then I can see (some) it happens all at once. This thing does nothing?

  3. local variables can lead to race conditions.  Output in Angle position may be a race condition, although is probably not what you wanted to do.  What does the wired local time at the moment present terminal meter? (Ooops! Two controls with the same name - which can be quite confusing as well!)  If you need or want two components of façade having the same text, use the legends.  Make the labels is different so the comic is more readable.

  4. having more than one Dequeue function on the same queue will lead to unpredictable results.  When an item is removed, it is removed from the queue and is not accessible to any other Dequeue function.  In parallel loops, you have no way of guessing which Dequeue will seize any particular element.

  5 use Boolean reverse instead of Select with wired False to true and true cable at the entrance to false entry. Better, just make the case of forgery in the structure of the case within the for loop the real deal. No required reversal.

  6. I was not looking for to determine the logic of the code within the structure of this case. It seems I could have posted a much simpler way to do this several weeks ago.

  7. use multiply from the Digital Palette rather than a node form multiply by 4 or 1.8. Uses less space BD and is much easier to read.

  8. as has been suggested, learn how to work the machine architecture and the State of producer/consumer.  They can make your life much easier.  Do not try to convert immediately to these models.   It's too much bite to at some point.  Learn how they work first.  Make a few simple examples.  Then rewrite this program in this format.  Probably faster than fixing what you have now.

  Lynn

• 2 parallel while loops with functional overall to share data

  Hello

  I'm having a problem with the sharing of functional with globals data between two parallel while loops:

  1. One of the loop (bottom) generates a random number periodically and write the total functional sample.
  2. Another loop (above) has a structure of event and when it expires, he would read the functional global and intrigue, a chart data point.

  The problem is sometimes the functional overall seems to be 'locked' and the output becomes zero constant. It also seems that whenever I first open the VI, it works fine. But for the second time running, he begins to have the problem.

  

  You must initialize your VI stop FGV FRONT of your lower loop begins.  Even if you use a global variable that is functional, you have a race condition.  FGV is read in the lower loop until it had a chance to be initialized with a value of false in the upper loop.  Functional global variables do not forget their data between executions of the VI.  So it is always set on stop the last time that you ran the VI.  This works your VI the first time it's because VI does not have in memory, so when it loads, it loads with the default value False in the shift register.

• for loop in formula node does not

  Hello

  I; m trying to use for loop in the node of the formula, but it is does not work. I want the output (y1) product value in certain range (a and d, and of course one is smaller than d). I ' do not use primitive labview since a and d are keep changing (both are variable). I tried to put "return 0;" after the y1 equation but the error popup.

  The issue of the loop works not because it gives the last value (I average would be ""). It does not begin with an (initial) value.

  Please help me how to solve this problem...

  Pls ignore other variables not used in the equation. Thank you!! A lot

  Your code works.

  

  But why you use loop?
  You get the last value, so you can get it in a single step with x correct;

  Also why you say that can not use primitives?
  If you use wire instead of terminals or local variable States values constant.

  Y1, y1_2, y1 3 is the same values calculated differently.

  

• For loop runs with the value of N unwired

  In this case will be a loop run connected to the loop N worthless? I have seen a few examples of the loop for run without a certain number of times set to be ran wired or for example a size of table or something like that.

  PauldePaor wrote:

  Here's a program I am and as you can see the image that the program runs without the loop N being wired. The program will run without problem

  As everyone else has said, you don't have to plug something on N.  If you wire up a table for loop for input "auto-index", the loop for will run automatically the smaller table size.

  Perhaps an example will help:

  

  This makes a loop on my table size (in this case, long of 5 elements).  On the edge of the loop for which resembles [] brackets, indicates that it is auto-indexé.  The loop should go through each item one at a time (1, then 2, then 3, then 4, then 5).

• For loop creates 1 d data table

  Hello, I am building the circuit below, and I'm running into a lot of problems with the loop, creating a table 1 d of data from certain types of data such as the ERROR OUT and the VISA NAME of RESOURCE. I understand why it does this, but I only need the last value in the table (the value of the last iteration of the loop for). This is true for me for the error, resource name of visa, and I was thinking of using the Boolean value that indicates when the for loop.

  Is there a simple way to extract the last value in the table 1-D so that it is correct to pass along trails, VISA and ERROR type?

  You actually create a block diagram, not a circuit.  A circuit is an electrical system including devices and wires.

  If you right-click on the tunnel and choose disable indexing, then you get the value of the last iteration rather than a 1 d table.

  I recommend you watch the LabVIEW tutorials online
  LabVIEW Introduction course - 3 hours
  LabVIEW Introduction course - 6 hours

• For loop tunnel exit "Last value" output of default values

  Salvation OR community,

  Today, I came across a probem of LabVIEW stange. A tunnel of release of "Last value" to a for loop back the default values instead of the last real value. The code is below:

  

  Below as screenshots of probes 44 and 45.

  

  

  When the probe 44 contains al the data (all the planks are present (and the correct "Testrack Module" is used)) probe 45 is empty.

  I already tried to remove the complete thread and it rewire. The result was the same.

  However, I also tried to use registers with shift instead of the tunnels and the code works now (see below for the code).

  

  The used version of Labview is 2013 SP1.

  I hope you can help,

  Tim

  Edit: If the images are too small, you can drag it to a new tab, and they become the original size.

  Tim,

  My first assumption: the because the loop never executes as you pass an empty array to an entry of automatic indexation.

  Another option, which is difficult to see in the screenshot: are there two entries of tunnels over the probe nr 42?

  Norbert

• FOR loop does not update the local Variable

  I am newer to labview, and I can't wrap the head around why not a habit of local variable to update in the code if it updates on the dashboard. Anything im missing?

  Assume that you are talking about the local variable of the 'State of the cell. The terminal updates every 500ms in the small top loop, the local variable indicates simply that the indicator and thus updates also.

  The problem is "dataflow" and you need to familiarize yourself with the concept!

  Once the while loop starts, the local variable is reading and inside the loop begins. Most likely, the local variable is read before it is updated in the small loop, so most likely returns the value of a fade on the first iteration of the while loop. Now the small loop continues to go twice per second for about five seconds. Only after the loop FOR (and everything else inside the while loop) completed, the while loop will go to the next iteration, date on which the local variable is read once more, this time with the last value of the last for loop iteration of the previous iteration of the while loop.

  In summary, the local variable updates very well, it's just that the code does not read the new value around most of the time.

  Your VI is full also potential competition conditions caused by the over-use of the local variable. You need to respect the proper execution order by eliminating local variables.

  So what is the solution? Hard to say without knowing what the VI is supposed to do. Most likely, you will need to remove the inside OF the loop and use it outside while loop for everything.