On a system running Gentoo Linux (3.1.6, x86_64), I have two six-core Intel Xeon CPUs (X5675).
cat /proc/cpuinfo correctly shows me 12 processors. However, I don't understand why the processor speed in the model name line differs from the cpu MHz number:
processor : 11 vendor_id : GenuineIntel cpu family : 6 model : 44 model name : Intel(R) Xeon(R) CPU X5675 @ 3.07GHz stepping : 2 cpu MHz : 1600.000 cache size : 12288 KB physical id : 1 siblings : 6 core id : 10 cpu cores : 6 apicid : 52 initial apicid : 52 fpu : yes fpu_exception : yes cpuid level : 11 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 popcnt lahf_lm ida arat epb dts tpr_shadow vnmi flexpriority ept vpid bogomips : 6133.17 clflush size : 64 cache_alignment : 64 address sizes : 40 bits physical, 48 bits virtual power management:
EDIT: htop shows all processors at 100%, and the load average is
24.66 24.33 24.67. So it seems none of the processors are idling. However, a
watch -n5 "cat /proc/cpuinfo | grep MHz" shows that the first six cores are constantly at 3067MHz, while cores 7-12 are always at 1600MHz. I'm puzzled.
I'm not sysadmin of these machines, but before I start bugging our sysadmins about this, I wanted to be sure that this is not the behaviour which is to be expected.
Is there any way to find out if SpeedStep is enabled without going into the BIOS, i.e. with non-root-priviledges?
EDIT2: as requested, I posted a full output of
/proc/cpuinfo here: https://gist.github.com/4683911