From mboxrd@z Thu Jan 1 00:00:00 1970 From: Meng Xu Subject: Re: Question about the CAT and CMT in Xen Date: Mon, 31 Aug 2015 16:09:31 -0400 Message-ID: References: <55E49C11.40303@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55E49C11.40303@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrew Cooper Cc: Chao Peng , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org Hi Andrew and Chao, 2015-08-31 14:25 GMT-04:00 Andrew Cooper : > > 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, Meng -- ----------- Meng Xu PhD Student in Computer and Information Science University of Pennsylvania http://www.cis.upenn.edu/~mengxu/