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Setting CPU Priority on NT/Citrix? 48

Broue Master asks: "I was recently faced with the task of finding a way to prevent some users from taking 100% cpu time in Citrix. I'm no MS certified anything (but I am a Citrix certified admin) and I couldn't find a built in way to do this. After someone on the NTSysAdmin List suggested trying to set the CPU priority to low from the command line, I investigated and found a small freeware that did the trick: PrioSet. I don't have a big user base: 3 power users (who are my problem with their Access and Excel use) and 10 regular users (and the people most affected by the problem). I'd like to know if any of you have previously tried this software, or if you've run into the particular problem when one user is getting 99% of the CPU for a long time while all other users only share the spare 1%. Did the software solve the problem or did you solve the situation by other means?"
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Setting CPU Priority on NT/Citrix?

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  • the old days...

    Though if you could find a way to do that, you might be able to convince your 'power users' to mind their manners. How about a contest every week...whoever uses the least CPU gets free beer?
  • command line (Score:3, Informative)

    by sql*kitten ( 1359 ) on Tuesday January 07, 2003 @12:33PM (#5033059)
    After someone on the NTSysAdmin List suggested trying to set the CPU priority to low from the command line, I investigated and found a small freeware that did the trick: PrioSet.

    Type start /? into the prompt - it can start processes at different priorities. So you can replace direct shortcuts to your applications with .bat files that in fact start the application at a different priority.
  • Easy (Score:3, Informative)

    by duffbeer703 ( 177751 ) on Tuesday January 07, 2003 @12:36PM (#5033111)
    Change the shortcut that users launch Access & Excel with to point a CMD, shell or Perl script that launches Access or Excel, then sets drops the priority. It's pretty easy to use Perl to launch and control office applications.

    Another route may be to move the access database to an RDBMS, which may use less CPU horsepower than using Access as a client/server.
  • NT on Citrix ? Wow, that's an archeological found :D !

    just kiddin'
  • Might not apply, but (Score:4, Informative)

    by Asprin ( 545477 ) <gsarnold@ya[ ].com ['hoo' in gap]> on Tuesday January 07, 2003 @12:45PM (#5033194) Homepage Journal

    If the problem is 16 bit DOS apps, Tame [] can help.

    Also, when you installed Office, did you run the appropriate app-tuning script afterward? (Search in x:\wtsrv for *.cmd and you'll find a whole bunch of them.) These scripts can make a big difference with certain versions of Windows.

    You might also try the MetaFrame Installation and Tuning Tips []. You might find a more recent version if you dig around.

    • What if he doesn't have an "x" drive. Is that a networked drive at your site?

      • I used X: as a variable since I don't know on which drive his %systemroot% folder is located. Citrix allows you to remap the local drive letters (C, D, E, etc.) on installation to something that won't conflict with the client PC's (M, N, O, etc.). This is taught in the Citrix cert classes, so he'll be aware of it.

        I guess on second thought, I should have sent him to search %systemroot% and avoided the issue, but I haven't managed a Citrix network in a few months, so I'm a bit rusty.

        • I'm sorry. I was trying to make a stupid joke but it was just that - stupid. I know to many IT/HelpDesk people who get real comments like "I just got a new computer and I can't find my J drive." It's kind of like "the internet's broken," or "the T1 is down," or "my AGP printer is busted."

          I knew what you were tyring to say, just trying to make a dumb joke.
          [hangs head in shame]
    • No one uses 16 bit apps anymore. This is 2003, for cryin out loud!
  • You can reduce the priority of the given app but any system processes used by it (api calls, drivers, software raid etc) can still use up that cpu/io anyway. Don't think I ever saw a workable solution for this, which is why i'm glad I don't have to write software anymore where I get told at the last minute 'oh by the way all the users will be running on the same citrix box'

  • by Anonymous Coward
    Dear slashdot; Some of my users are doing actual work, and it's making the rest of the users look bad. By doing work they show that we've bought underpowered hardware for too many users. How can I make them not do work so I get to keep my job?

  • How many DECADES have unices had ulimit support working by default? Wake up Micro$loth, here's another innovation you're completely missed the boat on.
    • Re:ulimit? jeez (Score:3, Informative)

      by larien ( 5608 )
      Ulimit isn't the same thing; ulimit limits on total CPU time, not % CPU at any given time.

      Thus, if they run an app for some time (e.g. over a few days) they might run up 30 minutes total CPU time with no real problems. On the other hand, someone could start an app, peg it at 99% for 10 minutes and completely hammer the server.

      Operating systems like Solaris have add-ons to achieve system limits like CPU allocations to individual users/groups, but that is NOT ulimit.

      • Fair enough. I was quick to reply, and ulimit cpu limits aren't quite what the guy is looking for. I bet if there was sufficient demand for such a thing, this could be hacked in as another setrlimit (ulimit) value with minimal effort.

        Just to continue being a "12 year old microsoft basher" as the AC response put it: Maybe we haven't seen a need in unix because schedulers work better there, and apps are better behaved?
        • Like I said, you can get similar things and Sun sell some resource management software which is used to guarantee that users/groups get a specified amount of CPU time. In short, there can be a need in Unix, although the schedulers do tend to work a little better.
  • by kevin lyda ( 4803 ) on Tuesday January 07, 2003 @12:58PM (#5033291) Homepage
    ask microsoft or citrix. go buy their books or their cdrom reference libraries.

    you paid for licenses and support, now go get your money's worth. why are you asking a bunch of (mainly) free software people who probably don't know the best answer?

    and if you think we do, why don't you use the software we use?
  • You can set the priority of any given task by right-clicking on the process in Task Manager. If you've got admin rights, and have "Show All Processes" ticked, you'll be able to set the priority for any user's task from within your Citrix session. I'm not sure whether this information will persist between sessions; you'll have to try that yourself. If you've got more than one server, put the three power users on one, and the other 10 on the other.
  • If you have a bit of C knowledge then you could write something to throttle the processes back via API calls. Simplest would be to find all the access processes (via toolhelp), then every once in a while enumerate all the threads in each process and suspend them for a fraction of a second (SuspendThread/ResumeThread).

    As long as the suspensions are done quick and often there is usually no visible difference, except that the process takes a lower percentage of cpu time. Admittedly I've only used this sytem before to make processes self throttling, but there is no reason why it shouldn't work for third party processes.

    Obviously it would take a bit of tuning to get right, particularly if the access processes aren't competing with anything else most of the time, but it shouldn't take more than a hundred lines of code.

    Erm, yeah, or you could just run them at a lower priority.

    • by borgboy ( 218060 ) on Tuesday January 07, 2003 @02:20PM (#5034053)
      Actually, if he's running Win2k server, he can use the Job Object API []
      This API allows you to set per-process limits on cpu, memory, user mode execution time, min/max working set, processor affinity, thread priority, UI restrictions, and security restrictions.
      I believe that Win2k Datacenter Server comes with a Job Object MMC for creating Job Objects / adding processes to a Job Object.
      • Yeah, I though about mentioning it, but it seems like he's tied to NT. I'm using them for the same thing that I used to use the manual throttling for, and they are great, particularly when spawning lots of third party tools like compilers.

        AFAIK they work on any W2k or higher machine, but I could be wrong; I don't think I use any machines that aren't server (rather than pro) for my stuff.

  • A similar problem (Score:4, Interesting)

    by Kj0n ( 245572 ) on Tuesday January 07, 2003 @01:56PM (#5033848)
    I once heard of a similar problem with a NT server running Terminal Server and several users accessing it from a UNIX machine. The CPU usage of Excel would suddenly go to 100% and stay there.

    Apparently, users used Shift + arrow key to switch to another virtual desktop. Unfortunately Excel went into a busy loop after the Shift key was pressed (it was busy waiting for the next key) and stayed there until the user switched back to the Terminal Server window. This resulted in Excel taking the entire CPU.
  • I know this is not the answer you are looking for, but wouldn't it just be so much easier to let the three power users run Excel locally on their own PCs rather than on the server? They are probably already using 800MHz+ PCs as the 'thin clients' - that is more than adequate for most Excel tasks.

    Unless they really need to jump from desk to desk, I'm sure they'd get much better performance, and the other users would be happier too.
    • Some thin clients really are just that; "toasters" with little/no CPU power.

      There's also the issue about licenses; while there may be licences for the server, buying licenses for all the clients might be expensive.

      • I'm pretty sure that with Citrix all the clients need software licenses as well. At least I think they do for MS apps. This should mean that there will be no licensing problems, assuming that the licenses used with Citrix can be used as local installations.
  • You buy proprietary software because you expect it to be supported. Go ask there. Or ask yourself why you are not. Or why you think you can run a product that you are not trained to administer.
  • You could try products from the company I work for. Check out Allows setting of CPU shares by user, and is highly customisable.
  • Access limited on CPU? Hmm you sure you are doing the measurments correct. I thought this was limited by disk and RAM.

    Likewise Excel can be a CPU hog or a disk hog, depending on what people are using it for, keeping lists of things or doing monster LP problems.

    How is the citrix server set up, does it contain all the apps and user data or is some off loaded onto other networked servers? I would suggest you need 300MHz of CPU per a user so for example 10 users=3GHz, say 2x1.5GHz Xeons/P4's, and at least one m/c to store user either user data on OR the applications i.e. seperate them to help avoid disk bottlenecks

  • This is a common problem with both NT4.0 Terminal Servers and Terminal Services under Win2K. Many applications, often written for the desktop, just don't play well in a multi-user environment like this.

    There are a lot of methods to calm down CPU-hogging apps. Some can be tamed by registry settings, others by utilities (like Tame), and others by server tuning apps like TScale, made by RTO Software [].

    All of these things are discussed on TheThin.Net [] website (and the associated mailing list), considered by many to be the best source of freely-available thin client computing info on the 'net. I suggest you check it out, and read the FAQs and archives.

    -Jeff Gunn

"It might help if we ran the MBA's out of Washington." -- Admiral Grace Hopper