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2 replies Latest Post - ‏2010-05-12T14:10:41Z by SystemAdmin
11 Posts

Pinned topic Controlling SMT on boot on POWER7

‏2010-05-05T21:20:52Z |
On SLES 11 running on POWER7,
I will prefer to start with no SMT, how do you control this ?
I saw that the command "ppc64_cpu --smt... " can set the SMT mode "off, 2 or 4" ..
I guess this is "root/superuser's privledge command?
Updated on 2010-05-12T14:10:41Z at 2010-05-12T14:10:41Z by SystemAdmin
  • SystemAdmin
    706 Posts

    Re: Controlling SMT on boot on POWER7

    ‏2010-05-05T22:18:21Z  in response to null
    You can boot the system directly into SMT=off mode by adding an smt-enabled=off string to the append directive in the /etc/lilo.conf file on SLES 11.

    For what it's worth, the ppc64_cpu command that shipped with SLES 11 last year is a little out of date, and cannot correctly set the SMT modes on POWER7.

    If you see this, you have the out-of-date version.
    # ppc64_cpu Usage: ppc64_cpu --smt             # Get current SMT state ppc64_cpu --smt=
    }    # Set SMT state   ppc64_cpu --dscr            # Get current DSCR setting ppc64_cpu --dscr=<val>      # Change DSCR setting   ppc64_cpu --smt-snooze-delay # Get currentsmt-snooze-delay setting ppc64_cpu --smt-snooze-delay=<val> # Change smt-snooze-delay setting

    Check out:

    Yes, ppc64_cpu is a root access command.

    There are ways to setup HPC environments which will allow jobs to set the right SMT level for each job. This would only be useful when jobs are assigned the whole compute node.