Will more function globals or sub vis slow down realtime DAQ or display

I need to do high sampling rate DAQ with varient data process and display.
Shall I intend to put all the code into one vi to accelarate the speed, or can I use more function global or sub vis to make the structure looks more reasonable.
Just worry how the compiler handle the data transfer when call function global or sub vis.
Will it creat new data copy and slow down the speed. Thanks.

The other 2 loops in charge of the data processing and display will keep checking the version of the 2 function global.
For high performance, you want to avoid this sort of thing. Basically, you're polling the functional global to see if it has new data. Polling will eat the CPU unless you include WAIT periods, but doing that slows your responsiveness.
Consider using custom events.
For the sake of discussion, let's say you need to process data in the TIME domain (1) and the FREQUENCY domain (2).
You create two events: NEW TIME DATA and NEW FREQ DATA, each carrying an array of DBL (the time-domain data from the DAQ).
The DAQ routine, when it gets a new data block fires both these events, feeding it the new data.
Your TIME DOMAIN loop (1) has registered for one event. When that event is triggered, the code accepts the data, and does whatever it needs to do (filters the time domain, graphs it, writes to file, averages, whatever).
Another loop (2) has registered for the OTHER event. When THAT event is triggered, the code accepts the data, performs FFT on it, and does whatever it needs to do (filters the frequency domain, graphs it, writes to file, averages, whatever).
Or you could do the same thing with queues.
When the use changes conditions, you change which event you listen to, or which queue you consume from.
The idea is that you want to avoid polling. Let the system tell YOU when data is available. Don't be asking the system if it's available.
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
Culverson.com
Blog for (mostly LabVIEW) programmers: Tips And Tricks

Similar Messages

Do I need to use a semaphore when reading/writing a functional global from reentrant VIs?

I have a program that spawns multiple reentrant VIs running simultaneously. These VIs write their status to a functional global. The VI that monitors them periodically polls this global to check out how they're doing and takes action based on their collective status. (BTW, I'll mention that this monitoring VI is NOT the parent that spawned the reentrants, just in case this might affect memory management as it pertains to my question.)
Anyway, 90% of the time, stuff goes off without a hitch. However, once in a while the whole thing hangs. I'm wondering if there's any chance that I've overlooked something and that some kind of collision is occurring at the global. If that's the case, then should I be setting a semaphore for the global read/writes?
And, if this is a problem, then there is something deep about functional globals that I don't yet understand. My notion of them is that they should negate the need for a semaphore, since there is only one global instance, which cannot be simultaneously called by the various reentrants. Indeed, this is arguably THE WHOLE POINT about functional globals, is it not? Or am I missing something?
Thanks,
Nick
"You keep using that word. I do not think it means what you think it means." - Inigo Montoya

Thanks Uwe,
This is a good hunch. However, functional globals typically run at "subroutine" priority. With this priority, it is not possible to select a specific execution system; it is always "same as caller."
I will try your suggestion by switching to "time-critical" priority. However, I do not know if this could lead to a different set of issues (non-determinism?). It will probably take a little while to hear back from my guys on whether this makes a difference or not, because the error is sporadic, and sometimes doesn't come along for quite a while.
While probing all of this, I looked at the execution settings for my reentrant VI. It has standard settings: "normal" priority, running in the "same as caller" execution system. My impression has always been that LV creates the clones with unique names. This allows the clones to be in the same execution system with no problem, and the fact that the execution dialog allows me to choose "same as caller" for a reentrant VI supports this assertion. This is logical, since there could potentially be many more clones than available execution systems. "Preallocate clone for each instance" is selected, which is what I want, I think, though I don't know if it matters in my application.
In summary, I am trying out your suggestion, but with skepticism. Any other suggestions from anyone out there? Any misunderstandings on my part that need clarification?
Thanks,
Nick
"You keep using that word. I do not think it means what you think it means." - Inigo Montoya

Will the iPhone 6.1.3 update slow down my iPhone 4?

I've been a little reluctant to update my iPhone 4 from ios 5.0.1 to 6.1.3 because I'm worried that it will severely slow down my phone. I had this problem happen to me before with my iPhone 3. Every time I updated the softwear, my phone got slower and slower. I like some of the new features of the recent updates to the iPhone softwear, but I'm just afraid that it will make the phone slower than it already is.
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Thanks, Paul

vhj wrote:
Don't update it, You will end up with poor battery life and bricked wifi like everyone else.
Sorry, but I disagree with your post. I have 4 iPhones in my household and none of them have poor battery life and the wifi is working on all 4 of the, so that shoots your theory out of the water, unless I don't count as part of "everyone else".

LabVIEW 8.0 computer slow down problem

When using LabVIEW 8.0/8.2 Full Development suite I have been experiencing times when the cpu usage of LabVIEW goes to 99% and stays there causing it to lock up and have to terminate the process. I have experienced this several times while working on a large program that I have been developing. I thought it was due to low memory but have upgraded to 1Gig of memory and still have to same issue. This will ussually happen when I make a change to the program or save the changes I have just made.

Dear Bjarne:
Are you able to see this issue with other larger VIs or, do all
the VIs slows down. Lets shift gears a
bit and see if now all VIs in the environment
are slow than usual. Just restart the LabVIEW environment, make sure no other
applications are open and that the CPU usage in the task manager does not show
its resources being used by another application. Then open up a brand new
VI or some of our shipping examples. If you see the problem while editing VIs and then try to save, it would be specific to the
environment you have installed. If it’s specific to the VI, I would take it to
a different system with LabVIEW 8.2 and see if that happens? Can you try
running the same VI on another LabVIEW development computer system?
http://digital.ni.com/public.nsf/websearch/862567530005F09C862565D40010CA3D?OpenDocument
http://forums.ni.com/ni/board/message?board.id=170&message.id=128375&requireLogin=False
LabVIEW will take little time (milliseconds to 1 or 2 seconds) depending on the
size of the VI to save if it’s a large project. Is this the behavior you are
concerned about? Can you try may be mass compiling VIs
in your environment? Please post some snapshots of task manager and the
VI size and the block diagram to help us speed the troubleshooting process.
Thanks much
Avi Harjani

How can I stop the loading of "Getting Started with Mozilla Firefox?", which has greatly slowed down the startup of Firefox.

Firefox used to start up fairly quickly, but now it loads an additional more complicated tab, which has greatly slowed down the start up process. How can I eliminate the loading of this time waster?

See these articles for some suggestions:
*https://support.mozilla.com/kb/Firefox+has+just+updated+tab+shows+each+time+you+start+Firefox
*https://support.mozilla.com/kb/How+to+set+the+home+page - Firefox supports multiple home pages separated by '|' symbols
*http://kb.mozillazine.org/Preferences_not_saved
Use this to go to the Firefox Profile Folder
*Help > Troubleshooting Information > Profile Directory: Open Containing Folder
*http://kb.mozillazine.org/Profile_folder_-_Firefox

Macbook Pro 2010 slowing down

I have had my MBP for almost a year now. It seems to be slowing down. I have 4g ram, 500 gig 7200 rpm hd, 2.4ghz processor and am running OSX 10.6.7. I use my MBP quite frequently using programs such as Microsoft Office 2011, iPhoto, iMovie and several others. I partitioned my hard drive so I have 350 gigs on the MAC side and 150 gigs on Bootcamp. I am a recent convert from Windows and I know that there are defrag programs for Windows and utilities to "clean it up" and speed it up.
Are there programs available for Mac to do the same thing? I am having more and more problems with iMovie and iPhoto slowing down considerably.
Any suggestions?

25 Ways to Speed Up Your Mac, your solution is probably in at least one of the items in this article.
Roger

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Will More Ram stop GB 08 from running painful slow ?
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It's true that more ram will make garageband run better, but I'm afraid that's not true in your case. I have a 2 year old macbook that had the ram upgraded 1 to 2Gigs and GB did run faster under heavy loads but I would say your processor and OS are maybe a little outdated if you're running GB 08. Then again maybe its something else but you have more than enough ram in my opinion.

RT executable causes functional global variable VIs to become non-reentrant

Hi,
I am having a small issue with functional global variables (Repositories). The attached VI is a sample functional global variable I created that stores double precision numeric values. The VI properties are set to normal execution. I use this VI to pass data between loops running in real time on a PXI platform. When running my application from the project explorer (not creating executable) the VI functions as it should and passes data between my loops with no issues. But when I create a real time executable of my application and run it on the PXI, it does not share data between instances of the VI. My work around this issue is to change the VI properties execution priority to Subroutine but it forces me to modify my VI slightly for this to work (I have to remove the property node). I am not sure why this is happing. I have seen some applications with this VI that appear to function normally in development and in executable with the VI properties execution priority set to Normal. Any comments or suggestions are welcomed.
I am running LabVIEW 2009, PXI-8186, and Windows XP
Thanks
Attachments:
RT Repository DBL Numeric Command Ver 2.ctl ‏5 KB
RT Repository DBL Numeric Element Ver 2.ctl ‏5 KB
RT Repository DBL Numeric Ver 2.vi ‏25 KB

Many properties require the front panel to be loaded in memory; the property you're using, NumItems, appears to be one of them (look at the help, you'll see that it says "Loads the front panel into memory.") However, VIs running in an executable on RT do not have front panels, so those property nodes will not work. If you were to log the error out terminal from the property node in your executable, you should see that an error occurs. As a result, you're getting a 0 value out of the property node, causing your VI to output unexpected results.
My recommendation is that you replace the property node with the function GetNumericInfo found in vi.lib\utility\VariantDataType. It has an output called EnumNames. Take the size of the EnumNames array and use that in place of the output from the property node. This will work on RT.
Note that this has nothing to do with re-entrancy, and the key hint is that the VI works when you remove the property node.

When trying to install Adobe Standard XI, it says, "Setup has detected that you already have a more functional product installed. Steup will now terminate." I have a Pro trial installed but did not seed so much functionality so I purchased standard.

When trying to install Adobe Standard XI, it says, "Setup has detected that you already have a more functional product installed. Steup will now terminate." I have a Pro trial installed but did not seed so much functionality so I purchased standard.

uninstall any acrobat and reader versions, if you have win os clean (Download Adobe Reader and Acrobat Cleaner Tool - Adobe Labs) and then install acrobat std.

Acrobat Pro XI will not install. Error says: Setup has determined you have a more functional product.

I have Standard XI installed and Pro will not install. Says Setup has determined you have more functional product. Setup will now terminate.

It may be that it is seeing the version number and not the product itself. All I can suggest is for you to deactivate and uninstall Std, then install Pro.

HT6058 Will this new update slow down my iphone 4 even more than the last update?

Will this new update slow down my iphone 4 even more than the last update?

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Will More RAM Slow Startup Times and Will it Speed Up Gaming?

Hi,
I was thinking of upgrading my Mid 2010 Macbook Pro's 4GB of Memory to 8GB (2X4GB).
I have heard roumors that it will slow down startup times. Also, it sounds obvious, but will it help with gaming performance and reducing lag during games?
Thanks.

"I use my Mac a lot in sleep mode so that is something to consider I suppose"
Don't let that concern you---it's not that big a pause. RAM is your friend. Thomas Reed's advice to use Activity Monitor is your best helper.
My older MBP has 2G RAM and can hold 6G, but AM has never told me I need more. Here what AM's RAM report looks like this morning:
44KB for "outs" is nothing, and the computer has not been restarted in days. (A restart clears the "in/out" numbers, so you should only run this test after using the computer for a while since the last restart.) On my MBP and for my usage patterns, 2G is completely appropriate. However, I've seen similar posts here where someone had 4G like you but the "outs were 25-30 percent of the "ins." Those people need RAM.

My newest iMac from a year ago is showing signs of slowing down its processing capability. Notice it especially in Aperture where I get the whirling dervish thing sometimes for a minute or more and once it crashed. Is there a way to "clean up the system"?

My newest iMac from a year ago is getting very sluggish. I notice it particularly in Aperture. I get the whirling dervish thing going on an operation sometimes for many seconds, even a minute or more and once it just crashed and I had to restart with the button. So I'm wondering if there is some way to "clean up the system" that is built into the iMac or if there is a reliable app I can obtain that will clean things up. I'm supposed to have a super fast processor in this version of iMac and lots of hard drive space and RAM. What gives? Any suggestions?

Things You Can Do To Resolve Slow Downs
If your computer seems to be running slower here are some things you can do:
Start with visits to:     OS X Maintenance - MacAttorney;
                                  The X Lab: The X-FAQs;
                                  The Safe Mac » Mac Performance Guide;
                                  The Safe Mac » The myth of the dirty Mac;
                                  Mac maintenance Quick Assist.
Boot into Safe Mode then repair your hard drive and permissions:
Repair the Hard Drive and Permissions Pre-Lion
Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer.
Repair the Hard Drive - Lion/Mountain Lion/Mavericks
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the Utilites Menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD disk icon and click on the arrow button below.
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported, then click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu. Select Restart from the Apple menu.
Restart your computer normally and see if this has helped any. Next do some maintenance:
For situations Disk Utility cannot handle the best third-party utility is Disk Warrior; DW only fixes problems with the disk directory, but most disk problems are caused by directory corruption; Disk Warrior 4.x is now Intel Mac compatible.
Note: Alsoft ships DW on a bootable DVD that will startup Macs running Snow Leopard or earlier. It cannot start Macs that came with Lion or later pre-installed, however, DW will work on those models.
Suggestions for OS X Maintenance
OS X performs certain maintenance functions that are scheduled to occur on a daily, weekly, or monthly period. The maintenance scripts run in the early AM only if the computer is turned on 24/7 (no sleep.) If this isn't the case, then an excellent solution is to download and install a shareware utility such as Macaroni, JAW PseudoAnacron, or Anacron that will automate the maintenance activity regardless of whether the computer is turned off or asleep. Dependence upon third-party utilities to run the periodic maintenance scripts was significantly reduced since Tiger. These utilities have limited or no functionality with Snow Leopard or later and should not be installed.
OS X automatically defragments files less than 20 MBs in size, so unless you have a disk full of very large files there's little need for defragmenting the hard drive.
Helpful Links Regarding Malware Protection
An excellent link to read is Tom Reed's Mac Malware Guide.
Also, visit The XLab FAQs and read Detecting and avoiding malware and spyware.
See these Apple articles:
          Mac OS X Snow Leopard and malware detection
          OS X Lion- Protect your Mac from malware
          OS X Mountain Lion- Protect your Mac from malware
          About file quarantine in OS X
If you require anti-virus protection I recommend using VirusBarrier Express 1.1.6 or Dr.Web Light both from the App Store. They're both free, and since they're from the App Store, they won't destabilize the system. (Thank you to Thomas Reed for these recommendations.)
Troubleshooting Applications
I recommend downloading a utility such as TinkerTool System, OnyX, Mavericks Cache Cleaner, or Cocktail that you can use for removing old log files and archives, clearing caches, etc. Corrupted cache, log, or temporary files can cause application or OS X crashes as well as kernel panics.
If you have Snow Leopard or Leopard, then for similar repairs install the freeware utility Applejack. If you cannot start up in OS X, you may be able to start in single-user mode from which you can run Applejack to do a whole set of repair and maintenance routines from the command line. Note that AppleJack 1.5 is required for Leopard. AppleJack 1.6 is compatible with Snow Leopard. Applejack does not work with Lion and later.
Basic Backup
For some people Time Machine will be more than adequate. Time Machine is part of OS X. There are two components:
1. A Time Machine preferences panel as part of System Preferences;
2. A Time Machine application located in the Applications folder. It is
    used to manage backups and to restore backups. Time Machine
    requires a backup drive that is at least twice the capacity of the
    drive being backed up.
Alternatively, get an external drive at least equal in size to the internal hard drive and make (and maintain) a bootable clone/backup. You can make a bootable clone using the Restore option of Disk Utility. You can also make and maintain clones with good backup software. My personal recommendations are (order is not significant):
1. Carbon Copy Cloner
2. Get Backup
3. Deja Vu
4. SuperDuper!
5. Synk Pro
6. Tri-Backup
Visit The XLab FAQs and read the FAQ on backup and restore. Also read How to Back Up and Restore Your Files. For help with using Time Machine visit Pondini's Time Machine FAQ for help with all things Time Machine.
Referenced software can be found at MacUpdate.
Additional Hints
Be sure you have an adequate amount of RAM installed for the number of applications you run concurrently. Be sure you leave a minimum of 10% of the hard drive's capacity as free space.
Add more RAM. If your computer has less than 2 GBs of RAM and you are using OS X Leopard or later, then you can do with more RAM. Snow Leopard and Lion work much better with 4 GBs of RAM than their system minimums. The more concurrent applications you tend to use the more RAM you should have.
Always maintain at least 15 GBs or 10% of your hard drive's capacity as free space, whichever is greater. OS X is frequently accessing your hard drive, so providing adequate free space will keep things from slowing down.
Check for applications that may be hogging the CPU:
Pre-Mavericks
Open Activity Monitor in the Utilities folder. Select All Processes from the Processes dropdown menu. Click twice on the CPU% column header to display in descending order. If you find a process using a large amount of CPU time (>=70,) then select the process and click on the Quit icon in the toolbar. Click on the Force Quit button to kill the process. See if that helps. Be sure to note the name of the runaway process so you can track down the cause of the problem.
Mavericks and later
Open Activity Monitor in the Utilities folder. Select All Processes from the View menu. Click on the CPU tab in the toolbar. Click twice on the CPU% column header to display in descending order. If you find a process using a large amount of CPU time (>=70,) then select the process and click on the Quit icon in the toolbar. Click on the Force Quit button to kill the process. See if that helps. Be sure to note the name of the runaway process so you can track down the cause of the problem.
Often this problem occurs because of a corrupted cache or preferences file or an attempt to write to a corrupted log file.

What's wrong with a "regular" global in this case? AND WIl ActiveX objects stored in functional globals remain valid (when used in an executable)?

I've written a plugin layer for a LV executable. When this layer makes a call to the plugins' initialization functions, I want each plugin library to be able to initialize and maintain its own global memory (where things like VISA resource names or ActiveX objects are stored). However, I've found that I can't manage to keep my global VIs "alive." I'm inclined to switch to functional globals, but I suspect that this will be a problem for things like ActiveX objects (that in this particular case reference a CAN interface). I believe that the functional global will indeed store the object from run to run, it's just that I'm somehow disinclined to think that the object will remain valid. I think you'll have to re-initialize it. Can anyone speak for or against this hunch? (If you can't tell, I'm trying to avoid building a whole little test executable just to debug this problem.)
I suppose the more profound question is "Why don't the globals stay in memory?" I'm attaching an image of what the application layer that calls the plugins' intializations looks like. Next I'm attaching an example of an actual initialization routine. You'll notice that I've even gone so far as to explicitly open the ref to the global VI that I want to keep in memory. Then I just leave it there dangling - but it still gets dropped! In my mind I shouldn't even have to do this, since the dynamically-called subVI "MC_CMO Init.vi" actually initializes the globals and runs with AutoDisposeRef = False.
Lastly, this is my first-ever attempt at writting plugin software. So if you look at my code and have any criticisms/pointers, I'll greatly appreciate them.
Thanks in advance,
Nick
"You keep using that word. I do not think it means what you think it means." - Inigo Montoya
Attachments:
AppLayer.JPG ‏60 KB
InitPlugin.JPG ‏103 KB

I am not sure if I follow you completely on your work-around.
Everything I have to say on this topic is based on obesrvations and threads I have read on Info-LabVIEW. Therefore it is subject to corecttion by those who know better.
LV is smart enough to know when "something" that had been opened, can be closed. It is not perfect.
If for instance you open a VISA refnum and pass the refnum to a LV2 AS A REFNUM the refnum in the LV2 stay alive as long as the VI's are running.
If you start another VI that uses the LV2 to fetch the refnum, it should get a valid ref as long as it starts before the first goes idle.
You then be able to work with refnum usign the VI launched second as long as stays active.
I often create action engine that can be invoked where required throughout an application. If the action engines get a ref in one state (like init) and use it another, I will generally write a "tester" that calls the action engine action to test the engine. In this case, my "tester" stays live and it keeps the ref's fresh.
I suspect if you tried to trick LV you could. If you type cast the ref nums to I32 and stored those in a LV2, I could see how LV could loose track of the resource sharing, but that is something I would avoid.
So I encourage you to do some experimenting with keeping track of who's running when to see if your work-around will work.
If you think you understand it better than I explained it, please post.
Trying to help,
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

How should I share a cluster across several sub .vis? Best practices? Current problems...

I'm trying to share a cluster across several sub .vis. I've written a save / load settings function that basically stores these settings in a static variable (full .vi attached):
Questions:
1. Is this an appropriate practice? (using a sub vi to share data)
2. My program settings appear to be lost occasionally and reset to their default values. This bug is rare, and it's hard to see what's causing it. Could this be caused by my "save / load settings"? Would this .vi result in race conditions or something weird if I use it in many places (and sub vis)? I've disabled reentrant execution.
The "save / load settings" vi above uses a sub vi to initially read the settings from a binary file and save them each time they are changed (saved). I initialize the "save / load settings" by loading the settings from text the first time this function is called.
Thanks!
Attachments:
Save and Load Settings.vi ‏82 KB
Save and Load Binary File.vi ‏62 KB

What you are doing is generally called a LabVIEW 2 Style Global or an Action Engine. It is a valid way to store data for use across subVIs. Rather than use first call why not have a specific action to initialize the data? The code is a bit more readable. Though you can use first call as you have.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

Will more function globals or sub vis slow down realtime DAQ or display

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