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Re: [Xen-devel] Question about the CAT and CMT in Xen

On 31/08/15 18:42, Meng Xu wrote:
Hi Chao,

I'm Meng Xu from the University of Pennsylvania.

We purchased a computer that has Intel(R) Xeon(R) CPU E5-2618L v3 @ 2.30GHz inside.
According to http://www.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html, Intel E5-2618L v3 should support both CAT and CMT.

I'm playing the latest Xen on the machine to evaluate how CAT and CMT work

The commit point I used is in the staging branch, commit 7b99717f62caeac08eea224a177cd28f047ac4b5, which was push on Aug. 17th, 2015.
I checked that the branch has merged your code.

After I boot up the system, I tried the following commands and it shows some errors.

My question is
1) Is there any specific BIOS configuration I need to configure?
2) The CMT is not enabled by default. Do I need to issue any command to enable it? I didn't find any document about how to enable it, according to http://xenbits.xen.org/docs/unstable-staging/misc/xl-psr.html. :-(
3) I'm not 100% sure if this machine we purchased supports the CAT. Right now, it shows "No such device" on the machine.
â But it may probably because the hypervisor forgot to initialize it?â

Below is the details of what I tried:

# xl psr-hwinfo
Cache Monitoring Technology (CMT):
Enabled     : 0
Cache Allocation Technology (CAT):
libxl: error: libxl_psr.c:96:libxl__psr_cat_log_err_msg: CAT is not supported in this system: No such device
Failed to get cat info

#xl psr-cmt-attach 0
libxl: error: libxl_psr.c:70:libxl__psr_cmt_log_err_msg: CMT is not supported in this system: No such device

Please let me know if you need any further information to confirm if the machine support the CAT or if it's because there is some issue with the software layer. :-)

Thank you very much for your time and help in this question!

Best regards,


To get started, use "psr=cat,cmt" on the Xen command line. Neither are enabled by default as they can potentially allocate quite a lot of resources behind the scenes.

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