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About QPI power state

John72
Occasional Contributor

About QPI power state

hello

 

Could somebody tell me which power state QPI enters while system is idle if QPI Power Management is enabled in RBSU?

 

L0p or L1 ?

 

If the answer is L0p, I wonder what kind of situation QPI will enter L1?

 

Thanks.

 

 

Server is DL360p Gen8.

1 REPLY
Suman_1978
HPE Pro

Re: About QPI power state

Hi,

 

I am not an expert on the QPI or processors but will try to answer your question.

 

In the BIOS settings, the option "Intel QPI Link Power Management" will be available provided if the server has multiple physical Intel processors.

This feature places the Quick Path Interconnect links into a low power state when the links are not being used. This reduces power usage with minimal performance impact.

 

According to Intel:

L0  = Link on. This is the power on active working state.
L0s = A low power state when the link is no traffic flowing over the link
L0p = A lower power state from L0 that reduces the link from full width to half width
L1  = A low power state with longer latency and lower power than L0s and is activated in conjunction with package C-states below C0.

 

Do check this Performance Counter Monitor from Intel to measure QPI.

www.intel.com/software/pcm

 

Also check this document from HP on Intel QPI settings in BIOS.

 

 

Thank You!
I am a HP employee
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