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Disabling Power Management - AMD Opteron in Linux

Last response: in Linux/Free BSD
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February 8, 2012 12:58:10 AM

I have a 2U server running AMD Operton 6220's. I am wanting to disable all power management that potentially will slow down performance. I noticed in /proc/cpuinfo the following:

processor : 0
vendor_id : AuthenticAMD
cpu family : 21
model : 1
model name : AMD Opteron(TM) Processor 6220
stepping : 2
cpu MHz : 3000.000
cache size : 2048 KB
physical id : 0
siblings : 8
core id : 0
cpu cores : 4
apicid : 32
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc extd_apicid amd_dcm aperfmperf pni pclmulqdq monitor ssse3 cx16 sse4_1 sse4_2 popcnt aes xsave avx lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 nodeid_msr topoext perfctr_core arat cpb npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold
bogomips : 5999.66
TLB size : 1536 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm 100mhzsteps hwpstate [9]

How do I go about disabling all of the items in the power management section? I've tried disabling everything I can in the BIOS but I haven't figured out where to play with the rest of these settings.

Thanks!
February 8, 2012 4:19:05 AM

jwgolf said:
...I noticed in /proc/cpuinfo the following:
...
power management: ts ttp tm 100mhzsteps hwpstate [9]
...

Just because it is listed in the CPU info doesn't mean that CPU frequency scaling/powerstates are enabled. Check some of the files in the sysfs, i.e. around /sys/devices/system/cpu/cpuN/cpufreq/*. It kinda depends on your distro and how (if enabled) it is handling cpu power management: you can usually get the desired effect by uninstalling something that is tickling those files on your behalf (one such package is acpid or apmd, but note that removing these, especially acpid, may have undesirable side-effects a la ACPI events no longer triggering events, like special buttons on the case).

If you really, really want to make sure you're getting the firehose, you can always download the kernel, use the config of the one you're currently running as a basis, and de-configure power management in the kernel itself. If you want to go down this path (it's not so bad, but you will get your hands dirty) let us know and we can walk you through it
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