From patchwork Tue Jan 10 07:42:35 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yi Sun X-Patchwork-Id: 9506623 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id DC421606E1 for ; Tue, 10 Jan 2017 07:45:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D011528156 for ; Tue, 10 Jan 2017 07:45:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C398028485; Tue, 10 Jan 2017 07:45:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 576B228156 for ; Tue, 10 Jan 2017 07:45:30 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cQr69-0004Le-Ct; Tue, 10 Jan 2017 07:44:01 +0000 Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cQr68-0004FN-4a for xen-devel@lists.xenproject.org; Tue, 10 Jan 2017 07:44:00 +0000 Received: from [85.158.137.68] by server-13.bemta-3.messagelabs.com id EE/37-25657-FB094785; Tue, 10 Jan 2017 07:43:59 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrFLMWRWlGSWpSXmKPExsVywNykWHf/hJI Igzk3xC2+b5nM5MDocfjDFZYAxijWzLyk/IoE1oztR1+yF2xQrtjxoZWpgfGSbBcjJ4eQQKXE /BcNbCC2hACvxJFlM1ghbH+J/cfaGbsYuYBqGhglzix+AJZgE1CXePy1hwnEFhFQkri3ajITS BGzwH5GifnHjzODJIQFzCU+dSwEa2ARUJV4c+IxUBEHB6+Ah0TTGSOIBXISJ49NBivhBAq3XF 3HCHGQu0Tz2/uMExh5FzAyrGLUKE4tKkst0jU20EsqykzPKMlNzMzRNTQw1stNLS5OTE/NSUw q1kvOz93ECAyHegYGxh2MnSf8DjFKcjApifKm6JZECPEl5adUZiQWZ8QXleakFh9ilOHgUJLg reoHygkWpaanVqRl5gADEyYtwcGjJMLLApLmLS5IzC3OTIdInWLU5Zj2bPFTJiGWvPy8VClx3 kCQIgGQoozSPLgRsCi5xCgrJczLyMDAIMRTkFqUm1mCKv+KUZyDUUmYtxlkCk9mXgncpldARz ABHRFpVwxyREkiQkqqgTH7XXFjdU690VXvpT8Pv4q9btkQZWg804lxLk/T/KVR0c0ct78f3HX 66rsefVtW2yD7PC2mzQqRXTebFBfeDrf/f/h3fuO/9w6M79bf+KOj+3vvJkerLmkfSV3FXtvf dbtSwld8543kW/nHTM54sW7RF55/LHcLjBJsGeVF18ZrnTU74rApXomlOCPRUIu5qDgRAJJRx hSNAgAA X-Env-Sender: yi.y.sun@linux.intel.com X-Msg-Ref: server-12.tower-31.messagelabs.com!1484034224!62972679!6 X-Originating-IP: [192.55.52.115] X-SpamReason: No, hits=0.5 required=7.0 tests=BODY_RANDOM_LONG X-StarScan-Received: X-StarScan-Version: 9.1.1; banners=-,-,- X-VirusChecked: Checked Received: (qmail 34099 invoked from network); 10 Jan 2017 07:43:58 -0000 Received: from mga14.intel.com (HELO mga14.intel.com) (192.55.52.115) by server-12.tower-31.messagelabs.com with DHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 10 Jan 2017 07:43:58 -0000 Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga103.fm.intel.com with ESMTP; 09 Jan 2017 23:43:58 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,343,1477983600"; d="scan'208";a="211583309" Received: from vmmmba-s2600wft.bj.intel.com ([10.240.193.63]) by fmsmga004.fm.intel.com with ESMTP; 09 Jan 2017 23:43:56 -0800 From: Yi Sun To: xen-devel@lists.xenproject.org Date: Tue, 10 Jan 2017 15:42:35 +0800 Message-Id: <1484034155-4521-17-git-send-email-yi.y.sun@linux.intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1484034155-4521-1-git-send-email-yi.y.sun@linux.intel.com> References: <1484034155-4521-1-git-send-email-yi.y.sun@linux.intel.com> Cc: wei.liu2@citrix.com, he.chen@linux.intel.com, andrew.cooper3@citrix.com, ian.jackson@eu.citrix.com, Yi Sun , jbeulich@suse.com, chao.p.peng@linux.intel.com Subject: [Xen-devel] [RFC 16/16] docs: add MBA description in docs. X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP This patch adds MBA description in related documents. Signed-off-by: Yi Sun --- docs/man/xl.pod.1.in | 35 +++++++++++++++++++++++++++ docs/misc/xl-psr.markdown | 60 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 95 insertions(+) diff --git a/docs/man/xl.pod.1.in b/docs/man/xl.pod.1.in index 2c41ea7..c101e0f 100644 --- a/docs/man/xl.pod.1.in +++ b/docs/man/xl.pod.1.in @@ -1787,6 +1787,41 @@ processed. =back +=head2 Memory Bandwidth Allocation + +Intel Skylake and later server platforms offer capabilities to configure and +make use of the Memory Bandwidth Allocation (MBA) mechanisms, which provides +OS/VMMs the ability to slow misbehaving apps/VMs or create advanced closed-loop +control system via exposing control over a credit-based throttling mechanism. +In the Xen implementation, MBA is used to control memory bandwidth on VM basis. +To enforce bandwidth on a specific domain, just set throttling value (THRTL) +for the domain. + +=over 4 + +=item B [I] I I + +Set throttling value (THRTL) for a domain. For how to specify I +please refer to L. + +B + +=over 4 + +=item B<-s SOCKET>, B<--socket=SOCKET> + +Specify the socket to process, otherwise all sockets are processed. + +=back + +=item B [I] + +Show MBA settings for a certain domain or all domains. + +=back + +=back + =head1 IGNORED FOR COMPATIBILITY WITH XM xl is mostly command-line compatible with the old xm utility used with diff --git a/docs/misc/xl-psr.markdown b/docs/misc/xl-psr.markdown index bd2b6bd..7d7f418 100644 --- a/docs/misc/xl-psr.markdown +++ b/docs/misc/xl-psr.markdown @@ -186,6 +186,66 @@ Setting data CBM for a domain: Setting the same code and data CBM for a domain: `xl psr-cat-cbm-set ` +## Memory Bandwidth Allocation (MBA) + +Memory Bandwidth Allocation (MBA) is a new feature available on Intel +Skylake and later server platforms that allows an OS or Hypervisor/VMM to +slow misbehaving apps/VMs or create advanced closed-loop control system via +exposing control over a credit-based throttling mechanism. To enforce bandwidth +on a specific domain, just set throttling value (THRTL) into Class of Service +(COS). MBA provides two THRTL mode. One is linear mode and the other is +non-linear mode. + +In the linear mode the input precision is defined as 100-(THRTL_MAX). Values +not an even multiple of the precision (e.g., 12%) will be rounded down (e.g., +to 10% delay applied). + +If linear values are not supported then input delay values are powers-of-two +from zero to the THRTL_MAX value from CPUID. In this case any values not a power +of two will be rounded down the next nearest power of two. + +For example, assuming a system with 8 portions and 2 domains: + + * A THRTL of 0x0 for every domain means each domain can access the whole cache + without any delay. This is the default. + + * Linear mode: Giving one domain a THRTL of 0xC and the other domain's 0 means + that the first domain gets 10% delay to access the cache and the other one + without any delay. + + * Non-linear mode: Giving one domain a THRTL of 0xC and the other domain's 0 + means that the first domain gets 8% delay to access the cache and the other + one without any delay. + +For more detailed information please refer to Intel SDM chapter +"Introduction to Memory Bandwidth Allocation". + +In Xen's implementation, THRTL can be configured with libxl/xl interfaces but +COS is maintained in hypervisor only. The cache partition granularity is per +domain, each domain has COS=0 assigned by default, the corresponding THRTL is +0, which means all the cache resource can be accessed without delay. + +### xl interfaces + +System MBA information such as maximum COS and maximum THRTL can be obtained by: + +`xl psr-hwinfo --mba` + +The simplest way to change a domain's THRTL from its default is running: + +`xl psr-mba-set [OPTIONS] ` + +In a multi-socket system, the same thrtl will be set on each socket by default. +Per socket thrtl can be specified with the `--socket SOCKET` option. + +Setting the THRTL may not be successful if insufficient COS is available. In +such case unused COS(es) may be freed by setting THRTL of all related domains to +its default value(0). + +Per domain THRTL settings can be shown by: + +`xl psr-mba-show [OPTIONS] ` + ## Reference [1] Intel SDM