VirtualBox 4.2.4 on FreeBSD 9.1-PRERELEASE problem: VMs behave very different when pinned to different cores

Andriy Gapon avg at FreeBSD.org
Wed Nov 28 15:24:39 UTC 2012


on 26/11/2012 09:10 Alex Chistyakov said the following:
> CPU: Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz (3200.18-MHz K8-class CPU)
>   Origin = "GenuineIntel"  Id = 0x206d7  Family = 0x6  Model = 0x2d
> Stepping = 7
> Features=0xbfebfbff<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,HTT,TM,PBE>
> Features2=0x1fbee3bf<SSE3,PCLMULQDQ,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,PCID,DCA,SSE4.1,SSE4.2,x2APIC,POPCNT,TSCDLT,AESNI,XSAVE,OSXSAVE,AVX>
>   AMD Features=0x2c100800<SYSCALL,NX,Page1GB,RDTSCP,LM>
>   AMD Features2=0x1<LAHF>
>   TSC: P-state invariant, performance statistics
> 

Is this a multi-socket system?

It would be very strange that a modern CPU like this would have such a skew
between TSC on different cores.

On my Core i5-3570 I see that the _observed_ skew is no more than 100 ticks (after
many days of uptime).  It could be zero, in fact, given the inaccuracy of
inter-core measurements.

-- 
Andriy Gapon


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