From patchwork Thu Jul 20 08:49:13 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yi Sun X-Patchwork-Id: 9854323 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 020A560388 for ; Thu, 20 Jul 2017 09:06:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EB0FF28782 for ; Thu, 20 Jul 2017 09:06:36 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DF59528785; Thu, 20 Jul 2017 09:06:36 +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 4B97528782 for ; Thu, 20 Jul 2017 09:06:36 +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 1dY7Nd-0007dm-Et; Thu, 20 Jul 2017 09:04:21 +0000 Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dY7Nc-0007Y3-7V for xen-devel@lists.xenproject.org; Thu, 20 Jul 2017 09:04:20 +0000 Received: from [193.109.254.147] by server-9.bemta-6.messagelabs.com id 03/E1-03406-31270795; Thu, 20 Jul 2017 09:04:19 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpkkeJIrShJLcpLzFFi42Jpa+uQ1xUuKog 0OH9F0uL7lslMDowehz9cYQlgjGLNzEvKr0hgzdj07xxjwWTliul9S5gbGHfJdjFycggJVEhM mNPDAmJLCPBKHFk2gxXCDpD4/mAJWxcjF1BNA6PE0UmvwYrYBNQlHn/tYQKxRQSUJO6tmswEU sQssI1J4v3lF+wgCWEBa4lVR3aCNbAIqEpsarwCNpVXwFPi5IWZzBAb5CROHpsMFucEij/v3s wOcZGHxL2Vf5knMPIuYGRYxahRnFpUllqka2isl1SUmZ5RkpuYmaNraGCml5taXJyYnpqTmFS sl5yfu4kRGBAMQLCD8cuygEOMkhxMSqK8LIEFkUJ8SfkplRmJxRnxRaU5qcWHGGU4OJQkeB8W AOUEi1LTUyvSMnOAoQmTluDgURKBSPMWFyTmFmemQ6ROMRpzbFi9/gsTx6sJ/78xCbHk5eelS onzLgUpFQApzSjNgxsEi5lLjLJSwryMQKcJ8RSkFuVmlqDKv2IU52BUEuZ9DjKFJzOvBG7fK6 BTmIBOeeQGdkpJIkJKqoGR+ffBaqlDOZ+djfNbZl6qWB+1eXET+5/zG/7YZOkuEdd8pXlS9Pm 35PVaSp+aH+1c8sjkOX/9bcdLVirzDPd4bO7IeXddfePFz7+UT7YErGVZ/q7f+OfNTx/ke2Yp 37iw7mfz/0ezNJLvnq1x2qas92X1zF8Hzihc+R48hy3Qp8pR7xAbw/MeVSWW4oxEQy3mouJEA AqucumUAgAA X-Env-Sender: yi.y.sun@linux.intel.com X-Msg-Ref: server-9.tower-27.messagelabs.com!1500541426!108131258!12 X-Originating-IP: [134.134.136.31] X-SpamReason: No, hits=0.5 required=7.0 tests=BODY_RANDOM_LONG X-StarScan-Received: X-StarScan-Version: 9.4.25; banners=-,-,- X-VirusChecked: Checked Received: (qmail 932 invoked from network); 20 Jul 2017 09:04:18 -0000 Received: from mga06.intel.com (HELO mga06.intel.com) (134.134.136.31) by server-9.tower-27.messagelabs.com with DHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 20 Jul 2017 09:04:18 -0000 Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga104.jf.intel.com with ESMTP; 20 Jul 2017 02:04:18 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos; i="5.40,383,1496127600"; d="scan'208"; a="1153387143" Received: from vmmmba-s2600wft.bj.intel.com ([10.240.193.80]) by orsmga001.jf.intel.com with ESMTP; 20 Jul 2017 02:04:15 -0700 From: Yi Sun To: xen-devel@lists.xenproject.org Date: Thu, 20 Jul 2017 16:49:13 +0800 Message-Id: <1500540553-29199-13-git-send-email-yi.y.sun@linux.intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1500540553-29199-1-git-send-email-yi.y.sun@linux.intel.com> References: <1500540553-29199-1-git-send-email-yi.y.sun@linux.intel.com> Cc: kevin.tian@intel.com, wei.liu2@citrix.com, andrew.cooper3@citrix.com, dario.faggioli@citrix.com, ian.jackson@eu.citrix.com, Yi Sun , julien.grall@arm.com, mengxu@cis.upenn.edu, jbeulich@suse.com, chao.p.peng@linux.intel.com, roger.pau@citrix.com Subject: [Xen-devel] [RFC v2 12/12] 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 | 33 ++++++++++++++++++++++++++ docs/misc/xl-psr.markdown | 60 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 93 insertions(+) diff --git a/docs/man/xl.pod.1.in b/docs/man/xl.pod.1.in index 16c8306..61f5bcb 100644 --- a/docs/man/xl.pod.1.in +++ b/docs/man/xl.pod.1.in @@ -1798,6 +1798,39 @@ 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 + =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 04dd957..59d93ef 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-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 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