This discussion is archived
8 Replies Latest reply: Feb 14, 2013 3:57 PM by athlonrob RSS

Of HyperThreading and C states...

athlonrob Newbie
Currently Being Moderated
Good Morning/Afternoon/Evening!

We've been validating as much of our configuration as is possible given our general OVM stability issues, and received a recommendation from Oracle to disable HyperThreading and C states for our x4470-m2 servers. We also found documentation that said we should disable VT-d, which we also disabled.

I'm wondering if anybody has any real world experience on these fronts. I'd rather have HyperThreading available if it won't undermine stability. They tech said generally you can't have Virtualization Extensions and HyperThreading on at the same time, but we're able to with our systems.

What kind of setups are you all using? We're on VM 3.1.1.

Thanks!

Rob
  • 1. Re: Of HyperThreading and C states...
    user12273962 Pro
    Currently Being Moderated
    I run 4 way 4470 m2 servers. Some with 8 core processors and some with 10 core processors. I also run some 4170 servers but I use the 4470M2 for all my database RAC nodes.

    What software version you running on the ILOM? I run v3.0.16.10.c r72950

    I tried running the latest before I went live and I had a lot of issues with the ILOM wanting to lock up on me. I reverted to the ILOM version above and haven't had any issue since. I use Oracle 7420 ZFS storage with FC for database LUNS/Diskgroups and NFS for repos over bonded 10GB ethernet links on Cisco Nexus switches.
  • 2. Re: Of HyperThreading and C states...
    athlonrob Newbie
    Currently Being Moderated
    Hi-

    We actually moved to the latest ILOM and have found our ILOM lockup issues far less prevalent. We updated just a week ago.

    Do you have HyperThreading turned on or off?

    Which build of OVM are you on? Is it generally pretty stable for you?

    Thanks!

    Rob
  • 3. Re: Of HyperThreading and C states...
    user12273962 Pro
    Currently Being Moderated
    The newest ILOM looks to be 1.3.1. I tried it and the web interface started immediately locking up on me when navigating. Even to the point I had to ssh into the ILOM and reboot it. I've been waiting on the second release of 1.3.1.etc before trying again.

    I don't remember if I disabled it or not. I don't know a way of telling without actually going in the BIOS itself. Do you know of way and I'll check what I have.

    I'm running 3.1.1-485 on everything and haven't had much of an issue. I have seen a couple instances in which temp files in the /var/tmp path would grow without much of an explanation of why but I've seen similar situation with non virtual Linux installations. Are you running powerpath? In the past, I've had serious issues trying to get multipathing to work properly with EMC equipment without powerpath. Not with Oracle VM just native multipathing in Linux. I almost purchased a EMC VNX5700 but couldn't bring myself to do it with all the unknowns with Oracle VM and powerpath at the time. EMC has since released Powerpath for Oracle VM 3.1.1.
  • 4. Re: Of HyperThreading and C states...
    athlonrob Newbie
    Currently Being Moderated
    The easiest way to tell if HyperThreading is on or off that I'm aware of is to see how many processors OVM Manager reports. I have two 8-core Xeons. If I have HyperThreading on, OVM thinks I have 32 cores available. If I have HyperThreading off, OVM thinks I have 16 cores available.

    Would you be interested in comparing notes via email?

    Rob
  • 5. Re: Of HyperThreading and C states...
    user12273962 Pro
    Currently Being Moderated
    I have Intel HT enabled. I show 80 processors on my 4 way 10 core 4470s.

    email is fine. I've never tried to do that here. I assume you have to enable it?
  • 6. Re: Of HyperThreading and C states...
    athlonrob Newbie
    Currently Being Moderated
    I don't know of a way to PM or email directly from the forums. You can email me directly at <<email redacted>> if you'd like to discuss. I would be very interested in comparing notes!

    Rob

    Edited by: Rob on Feb 14, 2013 3:56 PM
  • 7. Re: Of HyperThreading and C states...
    user12273962 Pro
    Currently Being Moderated
    Got your email if you want to remove it.
  • 8. Re: Of HyperThreading and C states...
    athlonrob Newbie
    Currently Being Moderated
    Thanks! I'll look forward to an email. :-)

Legend

  • Correct Answers - 10 points
  • Helpful Answers - 5 points