[prev in list] [next in list] [prev in thread] [next in thread] 

List:       xen-devel
Subject:    Re: [Xen-devel] Question about the CAT and CMT in Xen
From:       Andrew Cooper <andrew.cooper3 () citrix ! com>
Date:       2015-08-31 20:22:03
Message-ID: 55E4B76B.7070900 () citrix ! com
[Download RAW message or body]

On 31/08/15 21:09, Meng Xu wrote:
> Hi Andrew and Chao,
> 
> 2015-08-31 14:25 GMT-04:00 Andrew Cooper <andrew.cooper3@citrix.com>:
> > 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. But it may probably because the hypervisor forgot to \
> > initialize it? 
> > 
> > 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,
> > 
> > Meng
> > 
> > 
> > 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.
> 
> Thank you very much for your suggestion! Yes, after adding the
> psr=cat:1,cmt:1, the CMT works. Command "
> xl psr-hwinfo" shows the total RMID as 31. It means CMT is enabled/working.
> 
> However, the CAT is still not enabled on the socket. It have the same
> error message:
> Cache Allocation Technology (CAT):
> libxl: error: libxl_psr.c:96:libxl__psr_cat_log_err_msg: CAT is not
> enabled on the socket: No such file or directory
> Failed to get cat info
> 
> 
> I looked into the xen/arch/x86/psr.c and found that the function
> cat_cpu_init() just returned without initializing the variable
> "cat_socket_enable".
> 
> Both  !cpu_has(c, X86_FEATURE_CAT) and c->cpuid_level <
> PSR_CPUID_LEVEL_CAT are evaluated as 1 inside the function
> cat_cpu_init().
> 
> OK. I understand that  the cpuid info shows that the CPU does not
> support CAT. However, according to the table at
> http://www.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html,
>  Intel(R) Xeon(R) CPU E5-2618L v3 should support CAT.
> 
> I'm not sure which part is incorrect: the hardware or the software?
> (Hope Chao could give some insight about this.)
> 
> Best regards,

IIRC, CAT support required a firmware update on the Broadwell hardware
XenServer now has.

See if there is a BIOS update available from your vendor.

~Andrew

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel


[prev in list] [next in list] [prev in thread] [next in thread]