From patchwork Sat Sep 30 01:39:26 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Yi Sun X-Patchwork-Id: 9979009 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 3129560311 for ; Sat, 30 Sep 2017 02:01:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 18B6229592 for ; Sat, 30 Sep 2017 02:01:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0CF2F29899; Sat, 30 Sep 2017 02:01:24 +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 71A1929592 for ; Sat, 30 Sep 2017 02:01:22 +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 1dy745-0004lN-U1; Sat, 30 Sep 2017 01:59:37 +0000 Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dy744-0004XN-QS for xen-devel@lists.xenproject.org; Sat, 30 Sep 2017 01:59:36 +0000 Received: from [85.158.143.35] by server-5.bemta-6.messagelabs.com id 21/CC-03454-88AFEC95; Sat, 30 Sep 2017 01:59:36 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrKIsWRWlGSWpSXmKPExsXS1taRotv+61y kwZlPRhbft0xmcmD0OPzhCksAYxRrZl5SfkUCa8b8G59YC+5rVOx6uYmtgfGNYhcjJ4eQQIXE kub97CC2hACvxJFlM1gh7ACJW687WLoYuYBqGhglbi/+ygiSYBNQl3j8tYcJxBYRUJK4t2oym M0sUCnR9eAzmC0sYC3R3v+fBcRmEVCVeHVnIdhQXgEPidk7NjNDLJCTOHlsMlicEyh+raeJDe Igd4krLWsZIeoFJU7OfAI0hwNovrrE+nlCEKvkJZq3zmaewCgwC0nVLISqWUiqFjAyr2JUL04 tKkst0jXUSyrKTM8oyU3MzNE1NDDTy00tLk5MT81JTCrWS87P3cQIDEwGINjBuPO50yFGSQ4m JVHe3T/PRQrxJeWnVGYkFmfEF5XmpBYfYpTh4FCS4I0AyQkWpaanVqRl5gBjBCYtwcGjJMJrC 5LmLS5IzC3OTIdInWI05ji26fIfJo6Om3f/MAmx5OXnpUqJ8xaAlAqAlGaU5sENgsXuJUZZKW FeRqDThHgKUotyM0tQ5V8xinMwKgnzuoNM4cnMK4Hb9wroFCagUyZPPANySkkiQkqqgTH2v1Z HMHOL8I9JeWY8ToG7Vt/8Oj3pnuuzneYaq4N+HLw5i/eBu/kzcc7enrmsjGGZX2OiliStLbiw MJ8hYOrclUcN7D4Lm9wLrbWX6lhxgnPCZa9l4QsrvN+9sZeb0eCv1vSq+snZvbfT+MQmnWPSe vUxR6HU7ks+e6y5sfE9vV/9nCWPbiuxFGckGmoxFxUnAgBB36Bh2AIAAA== X-Env-Sender: yi.y.sun@linux.intel.com X-Msg-Ref: server-13.tower-21.messagelabs.com!1506736764!79487342!7 X-Originating-IP: [134.134.136.100] X-SpamReason: No, hits=0.5 required=7.0 tests=BODY_RANDOM_LONG X-StarScan-Received: X-StarScan-Version: 9.4.45; banners=-,-,- X-VirusChecked: Checked Received: (qmail 59025 invoked from network); 30 Sep 2017 01:59:35 -0000 Received: from mga07.intel.com (HELO mga07.intel.com) (134.134.136.100) by server-13.tower-21.messagelabs.com with DHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 30 Sep 2017 01:59:35 -0000 Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga105.jf.intel.com with ESMTP; 29 Sep 2017 18:59:35 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos; i="5.42,455,1500966000"; d="scan'208"; a="1020039149" Received: from vmmmba-s2600wft.bj.intel.com ([10.240.193.75]) by orsmga003.jf.intel.com with ESMTP; 29 Sep 2017 18:59:33 -0700 From: Yi Sun To: xen-devel@lists.xenproject.org Date: Sat, 30 Sep 2017 09:39:26 +0800 Message-Id: <1506735566-5706-17-git-send-email-yi.y.sun@linux.intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1506735566-5706-1-git-send-email-yi.y.sun@linux.intel.com> References: <1506735566-5706-1-git-send-email-yi.y.sun@linux.intel.com> MIME-Version: 1.0 Cc: Ian Jackson , Yi Sun , Chao Peng Subject: [Xen-devel] [PATCH v5 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: , 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 Acked-by: Wei Liu Reviewed-by: Roger Pau Monné --- CC: Ian Jackson CC: Chao Peng v5: - remove 'closed-loop' in 'xl-psr.markdown' (suggested by Roger Pau Monné) v4: - modify description of MBA in 'xl.pod.1.in' to be same as feature doc. (suggested by Roger Pau Monné) - fix words issue. (suggested by Roger Pau Monné) v2: - state the value type shown by 'psr-mba-show'. For linear mode, it shows decimal value. For non-linear mode, it shows hexadecimal value. (suggested by Chao Peng) --- docs/man/xl.pod.1.in | 33 +++++++++++++++++++++++++ docs/misc/xl-psr.markdown | 62 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 95 insertions(+) diff --git a/docs/man/xl.pod.1.in b/docs/man/xl.pod.1.in index 3d5f2f7..64d87ba 100644 --- a/docs/man/xl.pod.1.in +++ b/docs/man/xl.pod.1.in @@ -1803,6 +1803,39 @@ 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 by using 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. For linear mode, it +shows the decimal value. For non-linear mode, it shows hexadecimal value. + +=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..3d196ed 100644 --- a/docs/misc/xl-psr.markdown +++ b/docs/misc/xl-psr.markdown @@ -186,6 +186,68 @@ 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 by using 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 by the hardware). + +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] ` + +For linear mode, it shows the decimal value. For non-linear mode, it shows +hexadecimal value. + ## Reference [1] Intel SDM