From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: Question about the CAT and CMT in Xen Date: Tue, 1 Sep 2015 15:30:13 +0100 Message-ID: <55E5B675.7020607@citrix.com> References: <55E49C11.40303@citrix.com> <20150901054716.GA19417@pengc-linux.bj.intel.com> <55E5A263.5050708@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Meng Xu Cc: Chao Peng , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 01/09/15 15:20, Meng Xu wrote: > 2015-09-01 9:04 GMT-04:00 Andrew Cooper : >> On 01/09/15 13:55, Meng Xu wrote: >>> 2015-09-01 1:47 GMT-04:00 Chao Peng : >>>> On Mon, Aug 31, 2015 at 04:09:31PM -0400, Meng Xu wrote: >>>>> 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.) >>>>> >>>> Hmmm, from cpuid info it looks like this model does not support CAT. I'm >>>> not sure which microarchitecture it is. >>> According to http://www.cpu-world.com/CPUs/Xeon/Intel-Xeon%20E5-2618L%20v3.html, >>> 2618L v3 is Haswell. :-( >> Wikipedia agrees. >> >> Haswell only has plain L3 cache usage information. >> >> It is Broadwell which adds memory bandwidth monitoring, and Cache >> Allocation. > Ah, then the Intel's website [1] that lists the CAT-enabled processor > is quite misleading. I checked several processors (2618Lv3, 2608Lv3, > 2658v3) listed in [1] that is claimed to have CAT, and all of them > belong to Haswell... I think "v3" actually represents Haswell. > > Andrew, is it possible to know which processor XenServer is currently > using that is confirmed to have the CAT mechanism? I cant be much help, unfortunately, >>From /proc/cpuinfo processor : 14 vendor_id : GenuineIntel cpu family : 6 model : 79 model name : Genuine Intel(R) CPU 0000 @ 2.20GHz This is a 2-socket Broadwell-EP SDP and is probably a firmware revision out of date, but I can confirm that I have had a bit of a play with CMT and CAT on it. ~Andrew