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4 Replies Latest reply: Jul 31, 2009 8:55 AM by 807567 RSS

Changing from virtual to physical

807567 Newbie
Currently Being Moderated
All,

We are on Solaris 10, T5240 2 cpus, 8 cores, configured to run 128 virtual cpus. We are having major issues with our database program and the vitual cpu's and would like to make the box a simple dual cpu box. What are the commands I need to do this?

Thanks!

MM
  • 1. Re: Changing from virtual to physical
    user4994457 Newbie
    Currently Being Moderated
    You can use 'psradm' to disable any number of virtual CPUs (as long as one remains active).

    You can use 'pbind' to bind a process and it's descendants to a single (virtual) CPU.

    You can use 'psrset' to create a set of CPUs (maybe two in your case) and then you can bind existing processes or launch new processes to use only that created set.

    Any of those might be sufficient for your tests. The last one is the most flexible.
    --
    Darren
  • 2. Re: Changing from virtual to physical
    807567 Newbie
    Currently Being Moderated
    Thanks for the reply. Now with those commands I will be able to completely disable the virtual cpu "stuff" and have our server be just a dual cpu box correct? It seems that by running the psrset command to take processors offline I am really just taking any number of virtual cpus offline - we want zero virtual processors, like an old style 2 cpu box, if that makes sense.

    Mike
  • 3. Re: Changing from virtual to physical
    user4994457 Newbie
    Currently Being Moderated
    I'm not sure what you think the "stuff" is that can be disabled.

    The physical CPU appears to the OS as multiple CPUs.

    The most you can do is tell the OS to only use one VCPU on each core or on each processor. The VCPU virtualization layer is in hardware. It can't be modified (let alone disabled) in the OS.

    It would help if you could give more information about what you're seeing and why you think the virtual CPUs are causing problems. The individual threads (VCPUs) on the machine are slower than you would see on a very fast dual or quad core processor. There's nothing you can do to change that. The best thing you can do on this hardware is to run multiple jobs so that you still get a lot of work done. This hardware is very different and not every job will work well on it. That said, I don't know any reason that a database would do poorly. What behavior are you seeing?

    --
    Darren
  • 4. Re: Changing from virtual to physical
    807567 Newbie
    Currently Being Moderated
    Thanks for the reply Darren - and excuse my non-technical descriptions :-)

    The Informix database performance has at times shown extremely poor performance on the new servers, specifically for sql intensive jobs that run concurrently. See my 'Thread Migration' thread in this forum for more details.

    You answered my question though on how to effectively make the server a 2 cpu box. Thanks.

    Mike