Ubuntu
powerstat package

  1. Bug #1467014
  2. Comment #5

Comment 5 for bug 1467014

Revision history for this message
Colin Ian King (colin-king) wrote : Re: powertat -R erroneously reports no RAPL domains

RAPL was introduced on Sandybridge, so Arrandale does not support this, so perhaps powertop is incorrect. Powertop just reads MSR 0x611using:

        ret = read_msr(first_cpu, MSR_PKG_ENERY_STATUS, &value);
        if (ret > 0) {
                rapl_domains |= PKG_DOMAIN_PRESENT;
                RAPL_DBG_PRINT("Domain : PKG present\n");
        } else {
                RAPL_DBG_PRINT("Domain : PKG Not present\n");
        }

..and read_msr() in src/lib.cpp in powertop should return -1 if MSR 0x611 does not exist. So it is indeed curious that this does not fail. It's as if the MSR exists, but perhaps RAPL is not really supported correctly on Arrandale.

CPU model number 06 25 (Arrandale) does not support RAPL, tools such as turbostat detect the CPU ID and bail out for Arrandale, see http://sourceforge.net/p/openipmi/linux-ipmi/ci/a729617c58529be0be8faa22c5d45748bb0f12e5/tree/tools/power/x86/turbostat/turbostat.c, see lines 765-789.

I need to discuss this further with Intel